Sampling is not illegal, there is just a fairly fuzzy line regarding when you have to give a little to the source and that line is rather easy to work around if you don't want to share the profits. It is impossible to draw the line between fair use sampling and outright copying of anothers work and keeping that line fuzzy is better for hip-hop than a hard line. If the source could be identified through the sample than you give credit and seek permission, if you don't get permission or the cost is too dear than you learn from the past.

https://www.youtube.com/watch?v=_rlUQsC8ECk&ab_channel=Tommy...

Planet Rock was improved by their not being able to get rights to the Tans-Europe Express sample, their immitation may not be quite right to the original but it caused them to develop it and do more with it than they could have done with the sample itself.