I went through a cadet program and was flying for a major US airline in 4 years, starting with zero experience. It was supposed to be shorter than that but we had delays with COVID and other things. I wouldn't say it was 100% smooth, and you're still at the mercy of the overall job market and industry conditions. If your airline isn't hiring when you're done, then they're not hiring. They're not magically going to take only you.

But it was a lot faster to get to a major than if I'd done everything on my own. And while a lot of people were still talking about nobody hiring them right in this sub, I was in initial training.

So yeah, worth it. If you're thinking you're going to do this as your career forever, then the most important thing is to get to the airlines as soon as possible. Speed is all that really matters. Get that seniority number ASAP and start building your pay rate up. It does not matter if you have to pay a little more for the training up front. It might cost an extra $20-$30k now but you'll potentially make an extra $1 million or more by the end of your career as a result of that. (That's assuming hitting higher pay rates a year or two earlier through your entire career, and getting to the top level earlier too.) Even if it only gives you a few months advantage, that's more than enough to make up for the extra up front cost in the long run.