I know what transhumanism is, but people who are not, for example, academics in a related field calling themselves a transhumanist makes no sense to me. Like, as a transhumanist, what do you do?
Are these people just identity-hungry fans of a genre of sci-fi? Are they saying we shouldn't work to solve societal problems because technology will do it for us? Do they just watch a lot of youtube videos about it?
I've gone to class with, roomed with, and even worked alongside cishet mostly-white almost-all-male self-described "transhumanists" both within and around Silicon Valley, and here's my summary of 20+ years of knowing them:
They want a regressive version of the future, where there's immortality, superpowers, and a robot waifu goddess that serves their every whim
but is "friendly" enough to be subservient and only hurt and subjugate their perceived enemies.
Their brave new world would be basically 1950s suburbia, with 1950s demographics
and nothing too upsetting to them 
but with mass extermination of undesirables happening in the distant background, as a treat. 
No wonder so many of them were also massive blue-curtain-style Fallout franchise fanboys that really missed the point.
That subgroup may sound like a fringe, but they got money and power. The "Effective Altruist" grifters were from the same camp.
China started the war and Liberty Prime was unironic