Making your own CDs certainly doesn't mean that you can't get a record deal in the future and in any case it is a way to promote yourself. You won't sell millions - but these days even the biggest acts rarely sell millions (or even one million).

Having a physical release does help somewhat in promotional terms - I have had radio airplay because I have an actual CD - I also have placed my CD into a few shops (and they play it from time to time). You never know who might buy that CD - sell (or give) your CD to the right person and it might lead to bigger things.

Without a CD I wouldn't have any of that...

It's not an either/or thing. Putting out your own CDs won't stop you signing a record contract in the future.