Depends on whether you want to use their services? If you live somewhere where it's easy to just instantly transfer funds form one bank to another for free (e.g

Depends on whether you want to use their services? If you live somewhere where it's easy to just instantly transfer funds form one bank to another for free (e.g. you live in the Netherlands), then no: none of those companies need to exist in your world. If you live anywhere else, all these companies are offering services that banks don't, or charge much more for. Or these days, don't even offer themselves, they literally outsource it (e.g. sending money from one bank to another is now a built-in-third-party-service in the form of agreements with Interac to handle low value EFTs). So can you rival them? Probably. Will you fail? More likely than not. Is there lack of real competition? Depends on where you live, but yeah the whole reason they got this big is because they found a real problem and solved it, charging just enough for people to go "well that's still worth it for me".