Sorry to do this to you, but I'm going to re-direct back to the original non-fuzzy-violet question...
I've applied 3 times.
I've been selected 3 times (As Iggy mentioned, riding in one improves your chances of being drawn for another)
The 2nd time was totally different than the first (and 3rd) for a few reasons. Obviously, the events themselves are designed to be different each time. But also, when I showed up in 2009 I had no pre-conceived notions. I knew how to use my GPS & routing programs, liked my bike set-up, knew I could do some miles. Beyond that it was ALL going to be a surprise. Subsequent years you can't help but having some pre-conceived notions or expectations or ideas and chances are some of those are going to be completely wrong. SOMETHING is going to throw you for a loop, almost guaranteed.
I applied the 2nd & 3rd times because I knew I could do better. I was actually more satisfied with my first finish (26th) than I was with my 2nd (15th) because I felt like 26th was a good representation of my level of effort and I had reached my goals for that rally. The 2nd time I had a lot of screw-ups and bad luck that cost me several finishing positions and I wasn't satisfied that I'd done the best I could. I'm pretty satisfied with this year's finish, so we'll see how itchy I feel when application time comes around...
I think once you finish one IBR, and probably even before, most of the pressure just comes from yourself. But especially once you've got that 3-digit-#, you've shown you can do it. Lots of the very best riders have DNFs on their record because wins usually don't come without taking risks, but I don't think that leaves people (riders or spectators) questioning their abilities. There have been some big-name talents who have ridden multiple IBRs and done some just for fun, not trying to be competitive - it's up to you to decide if you're going to put pressure on yourself or just relax and enjoy the ride. No matter how you finish on subsequent rides, those 3-digits aren't getting any smaller.
My goals the first time were to be safe and finish as well as I could, no different than 80% of the field. I felt I reached that goal. The 2nd time was top 10 and I didn't pull it off. A failing microphone cost me two positions all by itself, then that whole eyeball thing, stupid routing mistakes, and Texas took care of the rest. Bad luck happens to everyone, but I was angry about my stupid mistakes and felt like I needed to redeem myself. So after being 90% sure that I wasn't going to apply again, I applied again.
You'll figure out what's right for you. It's expensive, there's no denying that. But it's also tough to see everyone out there being flogged and wishing you were there.
You did awesome this year and I have no doubts you'd do great in future years, should you choose to ride again.