I know im always thinking and yapping and unprompted sharing my thoughts but "protecting your legacy" is not a real thing and I need you all to absorb that. When you are on your death bed you will not think to yourself "wow im so glad I retired and protected my legacy". You will just feel regret, always thinking about what could have been. You will feel sad thinking about how you gave up what you liked doing to "save" an already cemented legacy.
Fernando Alonso won his championships in 2005 and 2006. It's been 19 years since he won a championship and it's been 12 years since he won an F1 race. Nobody says that he needs to retire to protect his legacy.
Jenson Button won his championship in 2009. His last race win was in 2012 and he didn't retire until the end of 2016. Nobody told him to retire to protect his legacy.
Should scientists who win a nobel peace prize retire to protect their legacy? Should people who win olympic medals retire? No.
A legacy is something that outlives you. Lewis could never win again and it wouldn't change the fact that he is a 7 time world champion. Back in the day it was common to win maybe a handful of races in your f1 career, and multiple championships if you were really lucky. We don't look back on champions past and think "oh, yeah, but he stopped winning". Nobody cares.
You shouldn't stop doing what you like to do, because what? you might "fall off"? A career of any sort has a natural life cycle, and letting that cycle run it's course shouldn't be anything to be ashamed of.
And besides. Like. Even if right now, any driver on the grid managed to win 7 championships, that would be their legacy. Lewis's racing career is only a small piece of a legacy that includes making way for POC in many fields, helping school children, supporting human rights, supporting women in motorsport. And your drivers legacy would be... what? Icecream? Being ruthless and mean? Tshirts...? Not kneeling for BLM? Publicly supporting Donald Trump?
Sure, Lewis has a lot of money, which is a different discussion all together, but it's important to note that continuing in F1 puts him in an amazing position to be able to do the things that he does. I believe the way that Lewis uses his wealth and fame, in more recent years especially, has been a net gain for society.
There is nothing anybody else on the grid could do to match him.
I've kind of said this before, but the only reason people think Lewis' greatness depreciates is because he's a black man. Especially because he's the first black man in F1. People who think Lewis needs to retire to protect his legacy are viewing him through this commodity/idol/deity lens instead of viewing him as he is. He's not a car, he's not a thing, his legacy doesn't depreciate or go up and down like a net worth. A legacy just.... is. Lewis has gained and changed and formed his legacy through his struggles and his triumphs, and he will continue to do that until he decides he doesn't want to anymore.
People will always, always, expect more from him as the first black man in F1. More pace, more wins, more anger, more calmness, more speaking, more quietness, more standing up, more standing down, more politics, less politics, more, more, more. He is held to an impossible standard that the collective of white drivers never will be because he's the only one.