400 out of 500 airlines who have played for 5 months did not manage to earn $5m. So BK and restart gets right to top 20% airlines, jumps ahead of 80% of airlines that have played for moths. Is it fair? I don't think so.
What's that based on? They haven't got their CV to increase above 9 million? Or have you looked at revenue?
I just tested, by joining & quitting GW#3. I'd rather have the 3 months extra growth in fleet size, RI, etc than the extra 5.5 million in startup cash. Sure, my CV won't have grown at all, it'll almost certainly be negative. But starting with an extra 5.5 million, my CV will be negative inside 2 gameweeks, too. 4 months in at big airport, I'd expect about a dozen planes, plus maybe a couple more ordered, decent chunk of slots, solidly profitable but no cash on hand. Start now and play for 2 gameweeks, so also 4 months in, and I'd expect 6-8 planes + their slots, but no RI, less profit, and also no cash on hand.
So, if you're a 'good' player, probably better off starting on day 1, though there's now more of a safety net for you, you can screw up, start over, have a clearer picture of what the competition is like, and not be as far behind as you otherwise would. If you're only an 'intermediate' player or a beginner, it's going to be easier to learn from your mistakes and start over in what is now a tougher market. If you're the sort of player who wants to BK all competitors, it's going to be tougher to simply squash anybody new who shows up in your airport.
Looks reasonable to me. It's possible it needs some balancing, my gut reaction is 5.5 million in ~100 game days is a little high, but hardly seems like a catastrophe. And as I said, I'd expect to be in a better position with 100 days of growth than I would be with 5.5 million extra cash.