Because economically, it's a non-starter.
You often spend a lot of money to get a job that pays very little in most cases ($20 000 p.a. as an F/O in the US), is no longer a career but a series of short jobs, mostly subject to poor management.
Some would say that if you had £100K burning a hole in your pocket it would be better spent starting another business.
I say that if it is genuinely your ambition, go for it, because life should be spent doing what you love (otherwise why bother?) but you should at least have your eyes open to reality.
If you are not sure, don't do it.
OK, back to some of your questions. A degree is not required to do the job, but some customers list it as a preferred option because of its perceived value (same as listing an IR for a VFR job).
I wouldn't restrict your thinking to airlines - there are plenty of other jobs that are rewarding - for example, if you got a float rating and built up some time (they like at least 500 hours) you could end up flying fire bombers.
It's good that you are bilingual - it's a good upgrade for a low time pilot.
And good luck!