Living 400, or 4000 years for that matter wouldn’t change my risk perception any. I’d just expect death to come during something I liked doing.
Being a geologist there’s a crapload of stuff I’d like to see/record that ain’t happening with 100 years but hundreds or thousands would make possible.
Also, in general, people would be in a lot less of a hurry if the time frame was stretched out. If you had a several thousand year lifespan when it came time to take a trip to the other side of the country walking with a pack or a cart is conceivable. People wouldn’t be in a frenzy to try to manage earning a living during their brief existence and fill their “bucket list” at the same time.
You could actually get a plot of land and undertake projects with decadal time spans (I’ll build a cabin here when these trees are mature in 50 years, these beavers will have this rocky wash modified into grazeable pasture in 70).
If we lived for centuries the impetus to jam all of the feelings and experiences we can into the brief window we currently have our physical and mental peak in would vanish (given a few decades to sink in). Most critically, we could uncouple ourselves from the shackles the “elite” have upon us by preying upon people’s general fear of death and desires to fulfill all of their experiential desires in their brief prime health window.
Being such a procrastinator as I am, I probably wouldn't get much more done in 4,000 years as in 40 anyway!