What is fusion energy that Jeff Bezos invested millions of dollars in this technology?

Is this the answer to the world energy crisis certainly going to take place?

Fusion energy is the energy generated in fusion.

Billionaire Jeff Bezos claims to invest a mountain of money in fusion technology . For a long time, people dreaming of water can hold the power of a star, but many obstacles have made that dream of "endless energy" unfulfilled. The two biggest obstacles of this industry are:

1. It has not been proven that this technology is effective enough for practical application. The amount of energy input is still greater than what fusion reactors bring.
2. The cost of building a fusion reactor is extremely expensive.

So what is a fusion reactor? Please watch the following video, created by YouTube channel Kurzgesagt, to better understand humanity's energy future (?):