People actually do NOT need money to work on games. Money is great, for sure, because if a dev can live off of donations, they don't have to work a regular job to pay bills and feed themselves. But, a person can definitely work a full time job for money to pay bills, and still have time after work to work on a game. The development goes slower, depending on how much they put on their plate at once. I.E: I am a musician. I do not get paid enough from playing shows and streaming, and selling merch, to pay my bills. I work a full time job. I still have tons of time after work each day, and on weekends, to work on music...which includes, but isn't limited to, practicing, writing, recording, promoting, booking, networking, interviewing, and google searching, and creating my own fliers....
I do all of this because of my passion for my art. It would be nice to be able to live off of it. But, as it stands, I need to play 4 hours of covers, in some run down bar in the middle of nowhere, 5 nights a week, steadily, while finding new venues regularly to not drown an area with the same band, just to make mediocre money. But all that is a different conversation. lol
Anyway...point is...money from donations is not necessarily needed to continue working on a game.