You don't need to mansplain it to me.Yes. Had he reported week 1 he could have had the $14.5 million this season and would still have gotten that $25 million contract with his next team. Heck he would have been close if to your hypothetical $25 million by signing the Steelers contract offer.
Now you can play the "what if he got a serious injury" game but he could have also lead the league in TDs, rushing yards, total yards, etc. Either could have a significant impact on a potential contract offer or perhaps not -- we'll never know.
The one thing we DO know is that Bell walked away from $14.5 million to play football in 2018 and that money is gone.
If he foregoes a guaranteed $14.5M today in order to get a guaranteed $25M tomorrow, then to me he didn't lose $14.5M. He actually gained over $10M.
You're free to interpret the situation differently.