Money, by itself, is not such a great motivator, though we are quick to think that it is the sole motivator of others. People who do things ONLY for money, tend not to do them so well.
Other motivators are: prestige, power, satisfaction, love, approval, romance, food, etc.
The absolute best motivations are usually combinations of those motivators.
My dear grandfathers knew this, and would frequently reward my good behaviors and learning successes with a small cash gift PLUS a kiss and a pat on the head, a few kind words of approval, acceptance and loving, and a small gift of sweet food.
That combination created a motivator for learning far more powerful than money alone. That continues to this day. I learn new things because I wish to, and get satisfaction from just knowing things, and I subconsciously recall the love, acceptance and gifts from my grandfathers.