JetBrains has outlasted most of the fully open source IDEs out there. Open source IDEs tend to suck and be abandoned after a while because there's no incentive to keep maintaining it, and it's expensive. See: NetBeans, Eclipse.

AFAIK the only IDEs in wide use today are open-core, like JetBrains' IDEs.

Me too, though I think it's a personal preference rather than an economically rational decision.

> rather than an economically rational decision

Depends on the time horizon