Look at this scale - there is no bonus for being in the lottery besides just a sliding scale of more money the first 3 years.
But to a 20 year old, the difference between 11 and 21(for example) amounts to 2 yr ~4.5m or 2 yr for 7 million. At 21 your family has $$ security still, and important to note the 3rd year options often are triggers for negotiating extensions so I don't even really take those into play here, but that would add another million delta.
Yes, its a couple million bucks, but keep in mind what you are gaining - you are now also adding another year to your earning potential, and you are a year closer to an extension, and you have reduced your risk of injury or poor performance to zero - you are getting paid NOW. Also going later means going to better teams with better development programs and less pressure.
I'm not saying that reasonable people can't look at those numbers and disagree - and when Calhoun made those comments in the late 90s early 00's the difference was greater in the payscale as everyone was not always slotted...
but in the modern environment - if you are projected in Rd 1 - unless there are mitigating factors, you just go.