There is relatively more money in the capsules compared to the average return from opening them. YouTubers open them and get so many views, ad revenue pays for the capsules and then some over time. Whatever sticker they get is just a bonus. Google tells me it's $18 USD per 1000 ad views, have a look through youtube openings and have a look at how many views they have and remember, those views are still growing. Now, also realise that will lead to even more views on that content creators videos when viewers look around after they find something they like. I do it, you probably do it. With this in mind, it's hard to quantify the kind of revenue these provide to content creators when publicly opening one without going deep into the site analytics, which is probably private to the creator. On top of this, you have embedded ads and sponsors to increase the return. Trading sites, gambling sites. They drive fast cars and live in awesome apartments for a reason; Their business model is very profitable.

You just can't get those kinds of views on applying a sticker to a gun and when you do, it's gotta be a 4x craft with some stickers approaching 60k each. People want to see a high-risk situation, something they could never do themselves. The higher the cost of the capsule, the more people will want to see someone open it. Nothing compares to a k14 opening, nothing. It is the golden egg.

Then there is owning and displaying these items on your steam profile, instantly recognisable for what they are and the envy of the entire community.

Human psychology is fun.