Because many tech workers don't see themselves as workers, with some justification, many having substantial capital investments alongside labor income, making them, in class terms, petit bourgeois or at least close enough to it to perceive their own interests in more bourgeois than proletarian terms. And even the tech workers that are clearly part of the proletarian intelligentsia tend see themselves (rightly or wrongly) on a path that leads into the bourgeoisie, with bourgeois interests.