Here's what I don't understand. Your platform is extremely popular, to the point where you're worried you'll hit saturation. Sure I get that.
But at what point do you decide "I SOMEHOW need more money, I'm running out of people." instead of being like "we're gonna make this service so good, everyone will have to go through us"
Netflix did this as well. When they hit a critical mass of subscriptions, they had really good shows. Instead of saying we're gonna stay the best streaming platform out there, they went "NOO yOU can'T ShaRe youR PasswoRds yOu SILLY person"
It's desperate and pathetic, and companies which fall this way will get no sympathy from me.
Companies hire junior devs (and other cheap labour) as "reserves", in the off chance that you get more projects (sometimes this is negotiated as a bonded contract, which you can't break for 3-5 years, but I hear that abusive practice is dying slowly).
They are paid abysmally low salaries, but youre not allowed to work, or find work elsewhere while you're on this type of contract. If a project comes and you're needed, you're put on a regular contract that is comparatively not as low paying.
All the factors you mentioned are still at play, these people are almost never put on existing projects, so you end up with less people doing more work, with more people just sitting around doing nothing waiting for new projects.
This type of environment is extremely negative and depressing to be in, and it promotes a lot of office politics to get yourself off that list and into a better salary etc.