Right, but to pursue that advance, you'd have to not have offered that book for sale. So the price of the lottery ticket here would be the $3600 you're forgoing by not self-publishing.So you're selling about 150 copies a month, or 1800 a year, for an annual return of $3600. A typical advance from a major publisher for a mass market paperback is about $6000...
You'd be betting $3600 for the chance to win $6000.
That means that if your odds of securing that paperback contract are any worse than 1 in 1.667, you'd be a sucker to make that bet.
Are you seriously proposing that everyone here making $300 a month [basically anyone with books in the top 8000 or so] has a 1 in 1.667 or better chance of securing a traditional publishing contract? That is absolutely ludicrous.
I would estimate that all of those people have a 1 in 1000 chance, or worse, of securing such a contract, if they pick up a pen and start writing query letters this very moment. So you're basically advising people to flush $3600 down the toilet.
If you had a family member with a gambling problem who was routinely making bets where they put down $3600 for a 1 in 1000 chance of winning $6000, you'd do an intervention.
The $ figures and reader figures a traditional contract can get you are nice, but they aren't the important numbers in the equation here. The important numbers are the opportunity cost of not self-publishing and the odds of actually securing a publishing contract starting from Square Zero. And the opportunity costs are known now, and the odds are absolutely dismal.