The original argument is flawed, and assumes that people’s political beliefs cannot be changed by experience. (That itself is a sad reflection on how polarised political opinion has become: political allegiance is being peddled as identity, rather than something that one is free to change as circumstances change)
But anyway, I’d argue that the reason why there are so few “right-wing” comedians is that the realities of being the entertainment business will undermine any support you might have had for right-wing economic theories when you went into it.
Precarious work arrangements, long periods of unemployment, a reliance on state-funded arts grants. If you came from money, that mightn’t be you personally, but if you go on stage regularly, that will definitely describe a lot of the people who are helping you, doing sound, rigging, setup, in other words, a lot of the people whom you go for a beer with after the show.
You’d need to be pretty self-centred to hear all of those stories over such a long period and still believe that poverty and hardship are purely down to a lack of hard work.
As for the nastier parts of right-wing ideologies, a job where success depends on you forming an emotional connection with a room full of strangers drawn from the modern UK’s multi-ethnic population is fundamentally incompatible with a belief system that people who look like you are innately superior to others.
(Mildly amused to see that a discussion of politics has turned into a discussion of “class”, that perennial British obsession. It’s entirely possible to be wealthy, work in a high-paying clerical job or —heavens!— live off the rent of your lands, and still hold left-wing political views, just as working in a factory is no barrier to being a fervent economic libertarian: after all, how do the Tories keep winning elections in a country with so many more poor than wealthy people?)