Not just from money, its mainly about time and effort. When you write a story and people read it, engage with the fictional characters, it gives a sense of fulfillment to you. Every comment makes you content with your work, pushes you to write more, better.
Reagrding the personal life, some writers do it out of fun, for some its a hobby, for some its a breathing room from their real world problems. We never know in what state the writers are.
As a reader personally, I've been stuck with paperback novels, non-fiction, academic books etc etc for a long long time. I had a very rough time in personal life with everything being super overwhelming and my sister suggested me to read some stories here. God I couldn't thank her enough, because I really felt some peace reading these funny fictional stories. Such is the case with many writers too.
When their work is plagiarised, it hurts them. If we compare to real world, lets say latest sensatiom Sally Rooney's book (like Intermezzo) is plagiarised. What will be a reaction and aftermath? May God help the plagiariser with legal battles.
IMO, sally rooney or ruhani gupta, they both are the same. CREATORS, AUTHORS. Every author, regardless of what story they write, good or bad or crap, their work should be protectes.