Read Leonard Nimoy’s bio. For years in the 50s and 60s he worked for $55/week for a speaking part, $25/week for a non-speaking part. A new show, new job every week if you could manage it. Survived on studio cafeteria left-overs. Don’t begrudge him a cent for the money he mad on Star Trek. He was never paid a dime in residuals from the the original series.
William Shatner was the only one smart enough to take advantage of residuals.
It’s my understanding that Star Trek really wasn’t expected to go anywhere, so nobody else thought to include residuals in their contract.