RBs arent taken with high picks as often as they use to be. Many teams find good or great RBs in the later rounds. Average career is what 4-5 years maybe? Look at Todd Gurley and Ezekiel Elliot. Two to three really fantastic years and then the wear and tear start to show.
From 2015-2019, 9 running backs TOTAL were taken in the first round. 2020 draft saw one, the last pick in the first round though 5 were selected in the second round.
Still would be a good pay day either way but NFL teams use high picks on corners, QB, DL and edge rushers. Just the way the game is played now.