This assumes a whole heck of a lot about how politicians view tax receipts and the budget in general. Governments simply don't find ways to collect less money. They find ways to collect more. And then spend the more, not send it back to the taxpayers.
Separately though, this proposal would not achieve your goal of helping "the people." It would do the opposite. First, if there is no incentive for the wealthy to lend or risk their capital, then they won't do it. Take away the ability for them to grow their wealth by lending, and they will just stop lending. That's not good for a lot of small businesses that depend on credit to operate their businesses.
Second, as the market dries up and becomes an uncompetitive government monopoly, individuals who need credit the most (lower and middle income types) will see the cost of their credit go up. If you truly doubt this, see Obamacare. Lack of competition kills innovation. It eliminates the incentive to build a better mouse trap and offer it for cheaper than your competitors do. So, when Joe and Suzy need a loan to buy a new car, today they can shop rates. A single lender system can't offer that.
Law of economics (much like the law of physics) doesn't seem to be your strong suit.