Seems pretty normal to me. I had a single laptop from 2010 to 2014, similarly to you, and it already started to feel gradually slower from year 2 until it died. Today I have another one that I bought in July of 2019 and it keeps doing fine. I barely download stuff, though, and barely use it, for that matter. Hopefully it keeps doing fine, I can't afford another computer this year, have lots of other expenses.
My bet with The_Liquid_Laser: I think the Switch won't surpass the PS2 as the best selling system of all time. If it does, I'll play a game of a list that The_Liquid_Laser will provide, I will have to play it for 50 hours or complete it, whatever comes first.