The correct way to look at this is net present value of each point. I'll show that each retirement point for mid-30s E-6 is worth about $75. Not bad if you can crank them out quickly.
Each point you earn, by completing a course, entitles you to a life annuity beginning from when you turn age 60 until the day you die. I'll show a simple example below for a 38 year old E-6 in the IRR. Let's ignore the survivor benefit, because that complicates things (it reduces the payout to the retiree in exchange for a potentially longer payout to the spouse).
Payment is adjusted for inflation, so no discounting of future payments is necessary (If I promised you $100 every year for the next 20 years, the fair value now would be less than $2,000, but if we adjusted the $100 payment for inflation, the fair value now may be about $2,000).
Life expectancy now of healthy non-smoking 38yo = 84yrs; this means we assume 24 years of payment for point earned today.
Base monthly pay for E-6 (2015 table) = $3,724
Monthly retirement pay for one point ($3,724 / 360 x 0.025) = $0.26
Net value of point earned today (24 yrs x 12 months x $0.26) = About $75
Could include effective tax rate in the equation, too. If I'm in a higher tax now than I expect to be in my 60s, 70s, and 80s, there's an even stronger case to do retirement points instead of taking a second job.
A high earner in California could have incremental state + federal + salary taxes of around 50%. Each dollar of top line income may result in $0.50 or less in the pocket. But in retirement, you will most likely pay less tax for a number of reasons (and moving to a tax-free state will certainly help, but might not be necessary).
Therefore, the current value of series of post-retirement life annuity payments that sum up to $75 may be equivalent to about $150 today, because of tax. To put $75 in my pocket now, I need to earn about $150. Or I can earn a retirement point and get myself some income deferred until the lower-tax future.