Lifespan of cooling fan

Hi,

I’ve been having a discussion with a colleague regarding the lifespan of a cooling fan. It is two years or 10 years? What are the determinants governing this?

For example, if a unit is being used daily for 10 hours would the cooling fan last five years?

Is there any research/stats on this? Or is it all anecdotal evidence, which is just as useful.

Thanks
nainish