Once you hit 30 and do what normal 30 somethings do (get married, buy a house, raise kids, drive estate cars) then a junior first officer at BA becomes difficult.
The factors I considered were Working Weekends, Holidays, Christmas. Buying a house in a nice area with a bedroom each for two kids near Heathrow/Gatwick is going to be a challenge at Cadet salary with 100k of debt.
Even at PP24/34 a large proportion of the business and first class cabins your flying will be better off than you. The money is good, but I wouldn't bank on being able to open an account at coutts.
Ultimately it is worth it, but those first few years are going to be very challenging...