Turning into IPL might solve financial problems but playing for India remains a dream for everyone, that's why the majority of them keep doing hard yards in the domestic circuit for years.
Money > Dreams for most people which is why those hard workers would instantly shift to leagues like the IPL if they got an opportunity.
If you didn't earn the Indian colors then it's tough. Generally, if you are not capped player then apart from the IPL, you will play domestic as well.
There is a reason that now BCCI is doubling down on players to focus on domestic cricket, they even signalled capped players that if they are free and fit then go and play for your respective state board.
BCCI is weird as hell. On one hand, they are primarily responsible for the whole crazy T20 boom in recent times and they are enforcing all of this stuff suddenly on the other hand. Bizarre!
Yeah, you can say that but BCCI has to look at the bigger picture. Domestic cricket is factory and cream players get to play for India. IPL is a bonus for them and it's same for many talented individuals from the domestic who are unable to cement their position in the national side because of competition, it could be any format.
If the domestic system gets weakened, the national team will face the same music and it's directly connected to IPL as it's money-making product because you need Indian talents and star value for your product. In recent times, a few capped players started to neglect Ranji, etc for IPL despite being free from the national team. It didn't sit well with the BCCI, hence the recent dictate.