Oh and Roosevelt did NOT serve 4 terms. He was ELECTED 4 times, but was already dying during his last campaign (this has been proven from records maintained at his Presidential library). He died less than 3 months after that last inauguration.
No President prior to FDR had ever even tried to serve more than 2 terms. Not one. The closest was his cousin, Teddy Roosevelt, who served one and a half, went out of office, and then challenged his hand picked successor and ushered the Democrats into office just before World War I, by splitting the Republican vote (if he hadn't run against Taft, Taft would have won hands down.) The reason why the amendments was passed, by 2/3 of the vote of each house of congress (including many democrats by the way) and then was ratified by 3/4 of the States, was that no one wanted to ever see another person decide that they were the "necessary leader" in the US again.
It took a LOT of Democrats to actually pass that amendment to the Constitution.
And Ronald Regan had no desire to run for another term. Only a few diehards fools were actually trying to promote that. He didn't want it, and told them to shut up.