Your post unfortunately reminds me of the old aviation saying,
" How do you make a small fortune in aviation?"
Start with a large one!!
With your limited knowledge you would probably rack up expenses so quickly it would astonish you.
Yes, you could buy an AOC from another company, but why do you think they are selling it? In the current climate it is very very difficult to make money in aviation, and that goes from flying clubs to air taxi, small charter companies to large airlines. By all means do your research, and the deeper you look the more obstacles you will uncover.
Yes, some people can make it work, but many others cannot.
Good luck with whatever you decide.