You're convoluting several things here.

First of all, even medium sized businesses often enough employ several people as their social media managers, not all in full-time, but there's already a big cost associated with just "being there". Then, you are severely underestimating what businesses usually pay for in support roles. Databases easily cost six figures in licenses per year, for example. All the MS365 stuff isn't free either. 500€ is a drop in the bucket - especially for marketing, and especially, if there are compelling enough features, to reduce SM-team staffing.

And finally, you're arguing ex post - the question/my point was: would it ever have been possible for him to turn a profit? You're basically arguing "the patient could not have been rescued at any point, as he is currently dead". Also, Twitter is definitely not "dead" as you're implying. Yes, user base is dwindling, but it's an erosion, not implosion.

PS: we're both using oxymoronic handles, so I guess we have to be best friends now.