That is easily contradicted
There is no contest between you and Grosjean unless you decide to make it a contest (in which case there is no doubt who has both more real world and theoretical expertise.
Look at the home.chicago.edu homepages and you can see that Grosjean was an undergraduate, or something close to it, up to the publication of his book round the turn of the millenium. He could not possibly have had a full-time AP lifestyle. The extent of his activities in Chicago make that perfectly clear.
He then appears to have undertaken post-graduate study until fairly recently (several news articles stated he was finishing a Phd). That would allow him more time as a player, but he would hardly be a full-time professional either, and he would have to spend a great deal of time travelling. In addition, he was fighting a court case, which is time-consuming. Now he's gonna be working anchor on TV or something.
He couldn't have played outside of the US for any significant period. Within the US, as we've established, he's been Griffinized, and he must have extreme difficulties getting a game. He's not an online player, nor does he seem to have any interest in sports betting, so no joy there either.
Now, I'm not that old, but I haven't/couldn't do much else. I've pretty much always been an advantage player since I was an adult. I have access to way more forms of gambling and some expertise in several lucrative markets US players don't even know exist. Within 2 hours of my home you could reach about a hundred casinos. In addition, I gamble extensively online. I cannot recall the last day when I did not place a wager.
In short: your assertion that Grosjean has more real-world experience than me, or indeed any regular green chipper, is ridiculous, and easily contradicted by the facts.