Think about computer science years ago. The internet was becoming a thing and people were making a lot of money on it. Everybody wanted to become a programmer, a web-designer or anything, just to be in the CS industry. Salaries were super high and it was exceptional to be there. As time passed by, the salaries got lower as the supply of CS guys (and girls) started to catch up with the demand. That said, the industry is still above average in terms of pay.
The same thing is happening to the data science industry right now. Demand is really high and supply is really low, so the salaries are still very high and people are very much willing to get into data science.
To become the expert, its recommended to join Data Science with Python course today.