He burned 22 billion because he was forced to after being a doofus. He is not destroying microblogging, he is destroying the environment around microblogging on his platform. It is his new toy that was never worth what he paid for it, so there is little point (to him) in trying to recoup monetary value. It’s value is to him is being his personal playground.
Garak is a simple tailor. He resolves an impossible situation in the least tailorly way possible yet somehow maintains plausible deniability.