Artists, by nature, are never rich. If they are they must have sacrificed art or integrity. Like Liszt said in the quote I use. If someone made a fortune out of art they must have made artistic sacrifices, otherwise they wouldn't have been able to make the money.
So if an artist is rich nonetheless this is because he or she is also a good businessperson and because the person was willing to sacrifice for money.
I would not seek for the sake of it to argue with you and I'd be the last person on earth to argue with Liszt, but I don't entirely agree. Let us expand the argument to encompass performers as well as composers. It is indeed true that what you suggest here is the case more often than not, but it does not follow from this fact that a performer or composer has to sacrifice something of his/her artistic merit in order to receive decent payment for his/her work. The immense fees that some performers receive do not, of course, serve as any kind of value judgement indicator of their worth as artists; neither, however, are they necessarily indicative of their being inferior artists. In other words, a truly great artist does not by definition deteriorate as such just becase someone decides to pay him/her large financial rewards for his/her artistic work.
In the case of the composer, it is only slightly different, in that his/her Estate can continue to benefit from payments in respect of his/her work for (usually) 70 years after his/her death, though these amounts will be dependent on many factors, not least of which is inevitably the number of major performances, broadcasts and recordings the music continues to receive during that time. During the composer's lifetime, his/her income from composition will also be derived from commissions; the amounts of these will similarly be dependent largely upon the extent to which his/her work is in demand at any given time. This, too, is not necessarily representative of any kind of value judgement of that music per se. So - if a composer gets paid plenty of money, it may not in all cases be as a direct consequence of his/her having sacrificed anything of artistic value.
Of course the originator of this thread was writing about composers of the past, whereas what I write here is largely geared to the present-day situation; with this discrepancy in mind, it is worth bearing in mind that Liszt's remark was of necessity based upon his experiences up to the time when he made it and, whilst I am not clear as to its precise date, Liszt himself has, of course, been dead for almost 120 years.
Best,
Alistair