If you can lift what you need to 50 times, do you need to improve strength?
For most people, exercise is about health and about being functional in their life. If you have a baseline level of fitness and an exercise habit that supports it, it is OK to plateau at that level and just live your healthy life.
It's not ok to plateau at that level. You will get old, your strength and bone density will go down and it is a lot harder (but still possible) to improve those when you are old.
Much better to start with a lot more than the minimum so you have a decent safety margin (and lifelong habits that will keep you healthy for as long as possible).
Most people would be better off lifting a 10 lb weight 50 times instead of lifting a 50 lb weight 10 times. High weight, low reps is a great way to injure yourself if you're like 99% of people out there.
And 10 reps is not low reps either. It's on the upper end of what people usually use in their workouts.