This just happens to be the consensus opinion for their group. Kids have never cared about being accepted by people 20 years older than they are; kids have always cared about being accepted by their peers. Social cooling means that dissent from their peer group is harder.
In sports betting contexts, you're often just betting against other players, I believe. If they're anything like prediction markets, the exchange isn't going to care how successful you are, as long as you're betting.
I enjoy thinking of trust as a social technology. We've seen how ridiculous a trustless transaction system would look with Bitcoin having to validate things to a ridiculous extent. Similarly, a society that distrusts wastes a lot of time and energy doing things by themselves, which is inefficient in the best case and leads down harmful and delusional avenues in the worst. We should be engineering our cities and communities with the intention of creating surface area for trust to emerge (e.g. public transit where we can just coexist in the same space), rather than mandating that trust ought to occur, since that isn't how brains work. Give strangers the opportunity to see that others are not so bad. We all prosper, economically and spiritually.