Even small donations help! Here's 2 ways to look @ it.
#1 That $50 you send in every year helps cover small expenses for traveling consultants, like meals for on the road an entire week.
#2 That $50 probably gets added to an account that draws interest, meaning that your donation grows from the initial amount you donated.
Some people will donate small amounts when they can their entire life- that adds up over 50 or 60 years!
Some people will wait until their more financially solvent and donate one lump sum. Which often helps out in an immediate situation. (Sometimes they will be people no one has heard of for 30+ years. And then, there's this big check!)
I personally donate small amounts nationally when I can. My alum chapter is beginning to work closely with our local collegiates, so I don't donate $$ to them. (They're actually pretty well off anyway, lol). If I ever become super-rich, then I'll definately donate a larger sum to them
I won't donate to my university until I pay off my loans, either. Although I'd like to think that when I do (about 6 more years) I'll donate occassionally.