That's why JetBlue has a never overbook policy. Having to deny someone boarding after they paid for their ticket and showed up on time is something we leave to those 'other airlines'.
Apparently turning a profit is something that JetBlue is leaving to those 'other airlines' as well. If you book the flight to capacity, the flight will go out with empty seats. PERIOD. Empty seats don't make airlines money. JetBlue's load factor has been declining. It is down more than 3.5% this year.
Smart overbooking is not a problem.