How many players are on a college roster? At the D1 level 35. At the lower levels many more than that. How many play? Lets take position players. You will have 8 starters who play the vast majority of the innings. One catcher who will rotate from time to time. A DH. And maybe one guy who is a utility player. Let's call it 11 position players who see time. That leaves 24 players. Out of those 24 you will have 3 weekend starters and 2 midweek starters. Then you will have around 6 guys that get the bulk of the relief duty. Lets call that 11. So that's 22 guys who see the vast majority of the time if not all of it. That leaves 13 guys.
Now think about D2 and D3. Many more players on the roster but the same type of breakdown in playing time. So who wants to sit the bench? No one does but someone has to. It's called competition. It's called working for opportunities. How can you run a program with no bench? I would suggest people just go look up random college programs and look at the stats from pervious years. Tell me what you see. It is not unusual for many D2 and D3 programs to carry 40 to 45 players on their roster. That was certainly the case in D1 before the 35 max roster limit.
The FACT is many college baseball players never start. Many college baseball players spend the majority of their time in college on the bench. If you don't love it enough to grind through adversity and are willing to spend your time on the bench working to get off the bench it's not for you.