I'm 45 and back in the 1990's I wanted to be a detective. No police agency would hire me though. At the time there was legal and open reverse discrimination. Then I gave up on doing police work to be a detective.
I was an Intel Analyst in the Army, and I've done a lot of private security work in the past. I went through six months of reserve deputy academy for my county only to be suspended for my political beliefs (defending individual liberty). Now I wouldn't dream of being a police officer, but I still wanted to do investigative work.
Because of my background though, I easily qualified in Virginia to be a PI. Now I can do the work I've always wanted to do. Even having the background qualifications and experience, it still took three years to get to where I am today as a registered PI with my own PI business.
The process is not easy, but at least it is possible in Virginia. Some state limit PI work to only former LEO's.
I have not worked with anyone else yet but would welcome the opportunity depending on the cause/objective.