People are actually paying to wear an ad?

OP acting like he seriously doesn't own a shirt with a logo on it.

Uhh yes. Often. First day on Earth?
- Must be Ford Prefect within a couple days after being stranded on Earth. The only logical way they don't know about branded clothing.

People pay for shirts with the nike logo on it all the time. Maybe folks think they're big enough now that they can do the same.

This is the main reason I hate branded clothing, With moth clothing they have branding on it and it's just an advert to the clothing brand. I personally hate this and try and find brands that are rather hidden / hard to see but also cost effective for me as I can't afford something super expensive especially for somethings small like clothing.

I mean, I wear band merch all the time, which is basically t-shirts, hats and hoodies that advertise the band.
- I was going to say the same. But I think there's a big difference between a band (art) and like the startup tshirts I've accumulated as "free swag" over the years (not art).
  A band is cool and human expression. Some website that sells ads in emails is capitalist nonsense.

Ever heard of brands?

I developed a distate for visible branding on my clothes and other items around 7 years ago and ever since I've gone out of my way to not buy any clothes with logos on them and I've been scratching away / putting tape over the logos on everything else.
- I feel like I became cognizant of this when I tried customizing my GTA Online character in something that wasn't a nice suit (street wear). After scroling through so much cotton billboard it made get how tacky and humiliating it is. Turned out to be much harder in real life to find non-branded shirts with cool designs, such utter bullshit.
  
  This is why I love furry stuff. Nomad Complex, Hyena Agenda and Weasel Gear are great. I mean, I guess Nomad Complex and Hyena Agenda could technically be kinda considered branded since Nomad Complex puts their logo on the front of their hoodies and Hyena Agenda has some shirts that incorporate their logo into the design, but the designs are generally really good.
  Edit: okay fine, it's one of the reasons why I love furry stuff.
- I've always had that dislike. I even do not wear clothes with text on them as I feel like I'm constantly saying that. Often the texts designers put on clothing is nonsensicalb stuff. F.i. Hollywood, I'm not from there, I've never been there, why would I want to say Hollywood the entire day?
  There's surprisingly little overlap between text people put on clothes and what I'd like them to say but there's a shitload of clothes the people feel like it needs some text on it.
  Anyway that's my pet peeve.
- What do you mean by putting tape over the logos? I’m imagining something like that you’ve duct taped over the front and centre Nike logo on a shirt but that seems silly
  
  Well, here's my laptop. In some other cases, on my camera for example I've just used black electrical tape and on my bike duct tape. I have used tape on clothing aswell, though. Many of my work clothes are from my previous employee but since it's in good condition I'm still using them but just have the company branding covered.

I stopped wearing any clothing with visible brand logos years ago. The only branding on my shirts is for bands and podcasts that I like.
- Same, except I got a Kirkland brand t shirt that's thick and comfy as fuck and I'll rep Kirkland all day (except their dishwasher pods fuck those).

Glad you asked me what it is. So you see, there are things call webpages. Yes, they are pages on the web. Guess what, there are people making them. Shocking, right? So part of the webpage…
- my favorite feature on this image every time I see it is the man on the right. pretty sure he is not amused about having to listen to what is happening behind him
  
  I kinda think of it as a memento mori... he's like: yep, that was me, 20 years ago... keep the sunglasses on son, now lean in and put your hand on her neck... yep, I remember those days...
  The not-quite-visible whitehaired person to the left only adds to the effect. Like: this is the inevitable course of your life, buddy.

Just like a band shirt, no?

from my perspective there are two types of t-shirt acquisitions: a) you need cloths b) you want to spread a message.
i would think most of the fashion brand t-shirts fall mainly into a) with a little bit of c) you want to be part of a superior group
most of the funny t-shirts and band-t-shirts fall into category b) and basically you also place yourself into a certain group but into a smaller, more specific one. the big fashion brands are arbitrary so many people can identify with them. they don't want to be associated with a real message, because then some people would be excluded from wearing that brand.
so the t-shirt presented as exhibit 1) certainly falls into category b). but i really can not come up with a message you want to send by wearing the t-shirt: it's not the "font-nerd" it's not the "web-dev-nerd" or anything like this. how big is the overlap of star-wars-fans and font-awesome users?
i think at the end it's just a marketing department that jumps on the latest bandwagon of internet memes in the hope that they can gain some popularity.
they could produce t-shirts that are fun to wear and spread the brand more subtle, but in this case i completely agree with op: this is a very strange campaign. and i also think that the comments here comparing this with fashion brands completely miss the point.

People pay huge amounts of money for clothes with adverts on them.

Isn't that an open source project? How else do you want them to make money?
- The old version from years ago was, the current version isn't. (Hence the existence of fork awesome)
- Don't think they are open source but they do provide a ton of free, high quality icons. Presumably they make money off the organizations paying for the icon packs.
  I'm not sure what OP has against them. He should take a look at how Nike has hypnotized a portion of the population into giving them money for shoes with a check mark.
  
  Nothing against them, it's just that it totally looks like a conference gift shirt, but indeed fashion brands brainwashed us to daily wear ads

Some random ass site making shirts will always be funny to me because why would I wear an ad for a odt to pdf converter

Idk what's the organisation structure, but they can be used as a gift for donators. The EFF does that and has pretty cool original tshirts than change every few years.

In their minds, they're wearing something to show off.

I don't get the appeal either, the idea of paying a company to advertise for them always struck me as odd, but I understand a lot of people, including content creators, mainly make money off merch, so I don't hold it against them.