I don't have any, but I do wonder if this is another reason why there's a bias towards younger founders (or at least the perception of one). You start a company at 25 after a few years of unfulfilling work, put your nose to the grindstone for 5 years, and, in this unusually terrible hypothetical, end up with nothing but lost time and opportunity.

But hey, you're 30. There's time for a comeback. There's no age limit on making a comeback, but I don't think it would be an outrageous claim to say that bouncing back at 30 is easier than bouncing back at 50. Of course, as is the case in most things, attitude matters. A lot. You can look at your 5 year struggle as a massive loss, or as an incomparable learning experience, and that could be the deciding factor in how successful your next venture is.