They just need to scale back their hiring excesses and bullshit jobs likely created.
https://www.politico.com/news/magazine/2021/04/16/how-substa...
the only value of the platform is in the creators, any team of devs can clone the product in a month. You're exactly right that they need barely any employees, because the technology isn't worth anything. The site has no moat or network effects so they will effectively need to subsidize the creators forever or not charge them anything, lest they run for the next platform.
It's the same reason the ridesharing industry is a profitless money pit. Undifferentiated, easily copiable products compete each other into the ground on subsidized investor money while owning no assets of value.
It's differentiated to something like Medium because I know I won't get ads, pop-ups, arbitrary paywalls, cheesy SEO content, etc.
Hopefully with the end of the easy money era this ridiculous business model dies out for good.