Why is there a need for most alt coins ?

Hello, I keep coming across good projects only to always come to the unanswered question: Why do they have to make their own coin/blockchain ?

The only case I could get behind is making a new "money-system" which is the case that I see Bitcoin taking with certainty.
For the rest, it feels mostly like a company or service being created and instead of distributing shares it uses some new in-house crypto-currency and I don't really see the point.

Like if you are creating a service why create a new monetary system specific to that service instead of using an existing one ? The only thing I could come up with is maybe getting funding "easier" as you open up the door for everyone to invest through buying the coin and without having to go through the hustle of regulations and paperwork etc which I am not sure if it is a good thing or not considering how many scams are happening in the space.