The others have made great points about how any amount adds up. Especially with compounding.

But the most important reason me just be making it a habit. If you are saving $50/month you have a place to put your savings and an investment strategy for that money. The next time you get a pay raise or get rid of some recurring spend it will be natural to start saving $60/month, then $100 and more and more. It is much easier to improve an existing habit than starting a new one. So as soon as you have the chance start that got habit.