How long do record players last? Do they still last a lifetime?

That depends, I dont know

 Your vinyl records can last anywhere from a year or two and up to well over 100 years. If you're aiming for the latter, it really comes down to how well you care for your record collection.

If you're talking about record players and not turntables to be used as part of a stereo system, then most of what's available today is such poor quality that they don't work properly in the first place. I'd imagine that they'd become unusable in a year or two at most,

They last about as long as a piece of food stuck between your teeth.

Phono cartridge with diamond stylus can last very long, 100 years perhaps.

Direct drive turntable also last very long, also 100 years.

Only the belt drive one doesn't las long, you need to change the rubber belt every (3 to 5) years.

bought a united audio german made turntable in lt 70s. smoked   wood/ semi dark clear cover lid,good cartridge,count the years it worked perfectly,no changer mechanism just a platter rather heavy,a belt 4 pole motor,4 speeds,small wires developed a short  a few months ago,,awaits repair I paid 40 bucks for it,used at a pacific stereo store on costa mucho california ( costa mesa) brought it back to chgo,,I did have to have some work done on it,then,another 50 bucks,dern things now sell for 300 bucks,about what it cost brand new

upscale audio shops carry models like the one in the statham movie the mechanic resurrection  1100 bucks,

most bog box stores carry types that crap out in 3 to ten years

Record players are junk. There is no point to buying one. A 1st generation iPod sounds better. Get a turntable, a receiver and a decent set of speakers if you want a record to sound better than digital music. 

You are wise to buy vinyl. Every time you use digital music Bill Gates knows where you are.

Some will last indefinitely if properly maintained.   

It is not reasonable to expect anything to endure forever without occasional service. 

They are a phjysical thing which over time wears out.  You may need to replace the stylus, there is generally mechanical parts within it that can wear down.  Like any device they can wear out over time.