I know you're framing this as a failure to raise, but believe it or not you're in a very fortunate position that most founders (including VC-backed ones) would

I know you're framing this as a failure to raise, but believe it or not you're in a very fortunate position that most founders (including VC-backed ones) would kill for. You have complete control of the decision and by the sounds of it relatively firm interest from buyers at a decent price. You can either take-the-money and move onto the next venture secure in life, or double-down and swing for the fences to see if you can achieve that $400m exit. Once you take external money, you lose that flexibility as your investors will usually dictate when and how you exit. If it were me, I'd cash out now but I appreciate it can be difficult to let go of your baby.