Think Laterally
Yes it is a huge investment - there are people who have spent 90K with no job.
Owing to financial issues including unemployment, rule changes from national to JAR, depressed airline market, etc, I took over 8 years to get a CPL/IR. Granted that was in the old days (1990s) when you had to get a BCPL then do 700 hrs before sitting CPL exams then build more time to do ATPL (CAA got threee exam fees that way!). Now you can get a frozen ATPL with only 250hrs. That's actually a lot faster and cheaper than the old system but you end up with a lot less experience.
Do not rule out Flying Instruction as an excellent way to develop flying skills (not only in others!). "OK, but why spend 6k when I can get a type rating with 20k......?", lots of wannabees ask.
Be careful what you hope for - flying a 737 five times a day as an FO with zero time on the ground to even visit "duty free shops" during turnarounds, early starts, late finishes, roster changes, and no g-tee'd weekends off, is not as glamorous as some people imagine! Lot's of airline pilots dream of actual hands on flying. With many Company SOPs now demanding autopilot use they tend to do most of the latter in a sim once a year! A long haul pilot might only get 2 landings a a month.
The industry is changing - there are instructor jobs out there offering GBP40k salaries and no i don't mean just the highly experienced Twin IR Oxford/CTC/Cabair postions.
Flying is something you must stay current on or interviewers will think you're not committed enough and you will feel less able to do a sim ride. Get him airborne at least once a month. If that is out of reach finacially, make sure he at least practices on MS Flight Sim or Xplane things like ILS approaches to minima.
Other job options options include local flying club ferry flying, freight flying with light twins, relief work in Africa on turbine aeroplanes, etc etc....
Above all don't give up without exploring ALL the options! All the best!