The people who come at you are a Studio or Publisher. It's rarely the author ever. Most like to see their work celebrated. The others are pure evil after money. Of course they might claim to represent the author. They don't. The author sold their soul. That network takes every pound of flesh. Far more gold and binding for the next a hundred years until a different publisher buys it or it merges.
As you seem to reference, it isn't the author because, at least with big successes, the studios have bought
all the rights they can possibly think of. (i.e. the Author doesn't come after you because it is no longer theirs, legally, at all). Where it is from an actual book author, the only exception might of course be the rights to future books, because those were almost always already in the hands of the original publisher, at least for the next few books.
Where you are possibly mistaken is in the belief that it is just about greed. No, the problem is the way that copyrights and other intellectual property laws function. If you allow
any breech of the rights, you will
lose those rights,
forever. The intellectual property can fall into 'common use', for example, meaning it can no longer be upheld as the property of
any single party, and negating all royalty deals, since nobody anywhere has to pay anymore. Failure to robustly find, and aggressively defend your rights negates those rights. The studio or publisher, by law,
MUST act to persecute any known transgression, or anything anyone who might want to take your rights away (to make their own use without paying you a dime) could feasibly argue in court represented abandonment of your rights, again, making it 'public domain'.
In the case of a studio or company having bought the rights from an author (usually with additional clauses about the author having to provide some additional support, as in appearances, statements, or promotions, etc.) they will
not be entitled to any kind of refund or discount if, after purchasing those rights, they lose them through failure to act, or allowing the rights to become public domain.
It's called parody. It's protected under fair use.
Calling it a parody doesn't necessarily mean it will meet the
legal definition of one. There's many, many cases of 'parody' works being challenged in court and the studio winning. Remember, the small amount of money an average 'parody maker' can make from a parody is absolutely nothing compared to all possible future revenue on the intellectual property rights (often millions, frequently billions), and so the studio or corporation can easily force up the legal costs to make it more expensive to even go to court than your parody was ever worth. Even if you win in court (which is a tiny proportion of cases), they'll immediately appeal, causing the whole costs to increase again, and they can keep this process going for years and years. As such it is extremely rare overall for a 'parody' defense to work out if there's even the least room for question.