From what I've seen it's extremely multi-faceted if you want to do the things described in the article (OS/binary zero-days), however there are somewhat simpler

From what I've seen it's extremely multi-faceted if you want to do the things described in the article (OS/binary zero-days), however there are somewhat simpler things to start with such as websecurity (XSS, request smuggling, fuzzing, sql injection, etc). There are many resources to get started (recommend some of LiveOverflow's videos) but one practical way is CTFs which challenge you in mock scenarios. Also financially & satisfaction-wise (at least if you are into learning/puzzling) it is quite good as something to pursue.