Hello ck, while I don't personally believe anything is "immoral", I understand that your friend's actions likely would be called that according to common ethical standards and nomenclature.
Obtaining academic qualification is supposed to be an exhibition of personal accomplishment and understanding. There are clear lines drawn for academic honesty with regard to work supplied for assessment. A person handing in fraudulent material would be acting "immoral" under that scheme... as you noted.
A person intentionally aiding that fraud would seem open to criticism along those lines as well. It would be like a person intentionally selling a gun to a psychopath who states in advance he is going to use it to shoot up his family (and this intention is clear). Or perhaps more analogously driving the getaway car for a bank robbery.
When the illicit usage of one's product or service is known in advance, and profits secured for such assistance, one becomes a participant in the act... not an innocent bystander.
From my own ethical outlook, your friend is dishonest, cowardly, abetting ignorance, perhaps greedy, and in some ways unjust (to all the others who actually work for their grade and the teachers whose time is wasted). If that friend is part of academic life, or that institution, one could also add the label disloyal. Certainly the person has removed their credible standing within academia.
Of course beggars can't be choosers. I'd likely do it if the money were right and my need great. The actual harm produced is very minimal and that's a large qualifier if one is looking at some great loss if the money were not taken.
Then again, if the person is doing it for extra spending cash, well I'd say the person's an asshole and ought to cut it out. Yet it takes all kinds to make a world.
One question your friend might ask, is if they'd be happy if while trying to get a position they got nixed from some SOB that used a fake paper to get their creds.
h
"Civilized men are more discourteous than savages because they know they can be impolite without having their skulls split, as a general thing." - Robert E. Howard