The chains are pretty durable...
IF
You change the Oil regularly
You keep the tension correct.
Also.. the smaller top spockets, with only around 9 or 10 teeth taking the full load of the power... those wear out and can damage the chain... the top sprockets need more attention, IMO than the chain does.
Also... You need to consider your chain as a safety item... If it breaks, you have no Brakes to stop... If it breaks on a hard climb... you will probably loose control... If it breaks often it will take out the chaincase and lock everything up... causing major problems... and maybe costing you getting stranded in the backcountry.
When a chain breaks... you have major problems usually.
I'm a big fan of pulling the chaincase cover when changing the oil... allows you to do a visual check that everthing is ok... and clean any debris really well.
IMO.. if everything is maintained/adjusted correctly... 2500 miles is a good estimate.
For a turbo sled, hard climbing... I'd do it every season for good measure... more than double the intended HP!!