It takes a lot less than you might think. It's the same branding strategy that outdoor sports companies follow, and they are generally not rich companies. There's far less money in the outdoor industry than the tech industry (I've worked extensively in both.)

Adventures sports are cheap. The athletes don't need much money to be happy, and the main cost of sponsorships are transportation.

But, that doesn't mean adventure sports are the right brand strategy for every company. It works for Red Bull because that's their business. It would not work so well for Uber.