I'm confused.....

Why on earth would you feel lazy by using your scooter? You have MS. Yes, there will be days when you don't need to use it. There will be days when you know you need to conserve your energy and, therefore, need to use it. And there will be days when you'll need to use it all day. There's nothing wrong with that.

If you were perfectly able-bodied and used it because you just didn't feel like expending the energy needed to walk then, yes, you'd be lazy.

It doesn't matter what others think - anyone who judges you without knowing why you're using it really doesn't matter in the big scheme of things.