So their estimates for taking a pool neophyte to these Fargo levels: 400(2-12 months), 500(6mo to 2 years), 600 (2-3) years, assumes 10 hours of table time per week, league competitive play, and professional coaching.
So reaching Fargo 400 could take ~260 hours, Fargo 500 ~1000 hours, Fargo 600 ~1500 hours
I don't think they touched on cost. If paying $7/hour table time to practice, that is $3500+ per year. Alternatively, you could buy a good home table for $3500 and be ahead after the first year.
Coaching could be $300/year online (estimating here), or $1200+ per year for a monthly session in person.
So reaching Fargo 500 in two years might cost you close to $10K?
These estimates were also assuming a young, physically able, and highly motivated student.
I hate to think how long and costly it would be for a retiree playing 3 hours per week to make it to 500.