The “YIMBY” movement is completely dominated by 20-40yo middle class professionals in my experience.
Plenty of tax breaks though.
YIMBYs also regularly support work on non-regulatory barriers, such as the rent increase caps in California (ABA1482), and have even supported social housing bills in California.
There's also lots of talk of transfer taxes amongst YIMBYs, see for example: https://cayimby.org/blog/if-you-tax-the-things-you-want-less...
There are two types of discussions about YIMBYs: 1) that by far-leftists that see the battle as ideological and about regulation/deregulation and trickle-down housing vs. revolution, and 2) the actual YIMBY activism on the ground which is all about more housing and making housing less of a financial and emotional burden for renters.