There's pride involved in:
a) wanting the translation to reach as many people as possible, not just one person, and not having it just die
b) not really accepting a paltry sum of money like 100~500$ for months of hard work
c) when it's money involved, the love and passion kind of get lost and it becomes a less noble thing
That's not to say it doesn't happen.
There's the obvious example of "D" and the company he works for purshasing unreleased rare Megadrive RPG localizations just to hoard them and release their own versions, but that's not really relevant here since they got permission (and appropriately paid) the Japanese/Chinese devs before selling their reproductions.
However, I have seen someone selling reproductions of NES games like the Jp version of "Yo Noid" and "Doki! Yuuenchi Crazy Land Daisakusen" for the Famicom, with the minimal text and graphics translated to English (after profiting off fantranslations by other people and trying to gut intros "if you paid for this you got scammed", some eventually wised up and learned how to do it themselves?)
But -- in these cases, an awful lot of buyers voiced their dissatisfaction with the quality of the translation - whether the text flow, the display bugs and crashes, the corners cut whenever possible...
So the situation can be shitty for the client commissioning the translation as well
And ---
Companies often aren't thrilled at the prospect of someone else profiting off their IP. Examples:
Engrish translations of Pokémon Gold/Silver before the official one, and of the Telefang games using the Pokémon name, getting C&D'ed by Nintendo of America.
The translations themselves are a bug fest with abysmal text quality and game crashing bugs aplenty, and Telefang wasn't released eventually outside Japan, but copyright owners didn't like someone leeching off their work for profits.
You mean some companies turn a blind eye to ROM hacking. Then you got bastard companies like Square Enix and others that give C&D notices.
Square Enix issued a C&D on two notable cases:
1° Chrono Trigger 3D remake: it reused the characters and assets in a way not controlled by Square and potentially damaging to the IP. It's a pretty reasonable train of thought for the sole reason if a company doesn't protect their IP in the US they can lose it.
It happens frequently when there are ripped assets/characters/game names used - Super Mario 64 HD and Streets of Rage 2 for example.
2° Final Fantasy Type-0: the translation patch itself was the entirety of the ISO data for both disks, making its take down more like a take down of a rom site.
The Chrono Trigger Crimson Echoes C&D wasn't confirmed.
Other high profile fan patches exist for other Square games and haven't faced their wrath - the Japanese overhaul hack for Final Fantasy VI for example.
(Square Enix IS a bastard company for other reasons though)
If you're looking for an evil company look no further than Konami. They were shutting down fan work very viciously even before the internet (Tokimeki Memorial, 1996)