What are the investments that earn fastest and highest returns?

Your question should be which investments earn the fastest and highest returns for a given risk. Remember the higher the potential return the greater the risk. It is not for nothing high-yield bonds are call called junk bonds. As an asset class stocks provide the best return over the long term, but within stocks you can find stars and stinkers, and the same is true of all asset classes. Don't invest outside your tolerance for risk, and don't risk money you can't afford to lose if you do buy high risk investments.

Real Estate

Winning a state lottery or winning on roulette in a casino. Other gambling, such as dice or slot machines also qualify. Of course the risk of loss is great. This is true of any high return investment. With very high risk, you have a chance of losing your investment or making a huge gain.

In the stock market, trading in stock options can provide a high return in a short time. Again the risk is higher than investing in the underlying stock.

Real estate also offers high return investments in a short time if you happen to find just the right property. Most investments return a normal rate of return. If everyone were able to earn high returns fast, we would all be millionaires.