I understand the most difficult part of becoming a barrister is not practicing smile or getting a degree, but getting there! I have heard that it is extremely competitive area and you virtually do not stand a chance if you do not have a mentor. Whilst with music, the ultimate talent will probably get you there (or am I naive?....)
Probably not so much naive as simply misguided. There is no evidence of any such thing as "ultimate talent" in music. That's just a label people attach to people like Maxim Vengerov to explain their success after the fact, because they don't find the seven hours of practice a day or the early first class teaching a romantic enough explanation.
And even if there were some respect in which those few outliers were "destined" by their talent for a success that no worldly considerations could stop, it wouldn't be relevant to the issue anyway because those people are only a miniscule fraction of the profession. What's relevant is the experience of most musicians and aspiring musicians, compared with lawyers.
I suspect being an international touring superstar is probably a pretty rewarding life, if an extremely tough one. I'd personally rather be one than a lawyer. But what's unusual about the music industry is not the condition of those at the very top (that's going to be pretty good in any industry), it's the steepness of the curve from there down to those earning nothing or almost nothing.
I'm sure it's bloody hard to get into Oxford, get a good law degree and make it as a top solicitor. The difference is that you can get into a lesser university, get an average law degree and still make a living as an average solicitor. There are thousands of such people sitting in offices all over the UK doing house conveyancing and whatnot, and quite comfortably paying their mortgages.
In music, a TINY proportion of those who practise their arses off all through their childhood manage to get a position in a professional orchestra (which is not, in itself, a particularly good living). Of the rest, some freelance for a few years until they give up and do something else; some drift into teaching or whatever. But there is no lower, broad level of the actual practical music profession like there is in other professions. If you're not in the tiny proportion at the very top, you do something else or starve.