Hi there,
I have two philosophies (of far too many) that I live by:
1) Future Regret Minimization
2) The greatest accomplishments come from temporary defeat
In terms of #1 What will you regret more in the future? Having tried a 3rd time (and, for the sake of this exercise, failed)? Or, not having tried a 3rd time? Think 2, 3, 4, 5 years down the road. What will you regret?
In terms of #2, I can't tell you how many people I've met who are at their lowest of lowest, failure after failure after failure, who finally "hit it big". If you dream you can achieve.
All this said, may not hurt to do the following:
1) Hire a coach for 1 session. Ask them to tell you, completely and honestly, "can I make it? Do I have what it takes". (Note, tell them that no matter the answer, you won't be paying for more sessions...coaches here are great but it doesn't hurt to remove bais/partiality)
2) Apply to other companies too. The other MBBs are great as are the Tier 2s/3s. They'll also give you training that may ultimately lead to McK down the road