Every time you raise a round, the outcome you're shooting for is magnified. If you're raising an A round, you're not getting acquired after your seed; you're rolling the dice on getting a much better outcome. If you're raising a B round, you've got some facsimile of product-market fit, and you've decided to take the company to the point where the only "successful" outcomes are denominated in hundreds of millions of dollars, etc.
So it's not surprising that there's a stat somewhere that says "committing to a 500MM sale decreases your odds of success over satisficing with a 50MM sale", right? Very few software companies of any provenance end up going public, but by the time you're raising a C, that's essentially what you're saying you're going to do.
It gets even worse, because a proportion of those raising another round are doing it because they're failing to grow fast enough, and are grabbing more cash before it's too late.
So you get a mix on those rolling the dice one more time in the hope of that next 10x, and those unable to get an exit, and unable to earn enough, but able to convince investors one more time that this round will pay off, and who will rarely pay off well for founders or early investors, if at all.
I've both been in companies like that and worked for a VC analysing round data to avoid putting money in companies like that...
In a company like that, I once got 10k for my original 25% stake when the company was finally acquired... I left after the 4th round or so, and there were at least a few more after I left (I stopped.paying attention. The company was acquired for only 40% above the size of the A round.
Once you're in the VC cycle though not being able to raise another round when you need it is a 100% decrease in your chance of success. So I'm not sure if that follows for any but the first. Essentially you need to keep raising until you either reach profitability at scale, are acquired or IPO, and even the latter won't help you if you aren't eventually profitable.