To gain trust, a sportsbook must be trusted and can provide unique services which have licenses and certificates. As well as having cooperation with international agents to provide the most complete sportsbook services.
Have you ever heard about 1xbit? I think 1xbit fulfill your criteria (especially about license) to be trusted sportbook, but what is the fact? They are not trusted at all. Licenses is not a guarantee to be trusted gambling site, most early crypto casinos had no license but they can get good reputation because they can prove themselves that they are reliable and worth to trust.
You are right, license is not what people is looking at for now, what will describe who you are is your site reputation, because you may have goid license that permit your gambling operation but people is complaining of your deposit and withdrawal. And especially when you win no body will give you privilege to withdraw your cash, this is what brings the reputation of gambling site down, don't play with casino game and cryptocurrency game, a reduction of trust started when people complain you don't pay when game is being won in your site, example 1xbit and no body trust them because they carried money of gamblers away, no payment