Twitter's mMAUs (monthly Monetizable Active Users) stands at 450 million. If they pay $8 per month, that gives Elon $3.6B per month. It will take 13 months to make $44B - the purchase price QED. Elon Musk is a genius.
The biggest question is will you, I'm living in a third-world country and I only have Twitter to check the latest news and current events, $8 is big money to me I prefer to buy groceries with it, than stay verified and there are millions like me, those who will stay verified are celebrities and Elon supporter, he can still make a profit but not what you projected that he will make in 13 months, it's far from it.