Team’s own funds and a bigger vision are enough to let early supporters profit,

but at the same time you also need to be ready to “run alongside” them, because as long as the project makes money, they won’t think about TGE early.
Issuing tokens is a debt, so what is the debt for?

It’s definitely to make more money. Projects with funding will also have pressure from investors to exit, and there are contract-related restrictions too.
So unless issuing tokens would make the project worse, or the mortality rate increases,
otherwise most project teams will choose to issue tokens