Ultimately, that’s the point everyone seems to agree on - bike thieves are assholes. For everything else, there is little consensus and hard evidence. However, some things are clear and explain a lot of the bike theft that occurs.
It’s dead simple to steal a bike and the consequences are near zero. You can resell stolen bikes. If you want to get a good price for a stolen bicycle, it requires a decent amount of work. That amount of work is what limits the bike theft trade from really flourishing. Criminal masterminds have an opportunity cost for their time; they can’t be messing around lugging heavy pieces of metal and rubber that are only in limited demand.