The odds on the domain being viable in a timescale that makes the regging of it rational, must be truly galactic. There's a reason we don't see domains that if true would be worth millions topping search terms. "freeneverendingcashforyou.net, liveforever.io, growtaller.com, neverdie.org.uk, and probably the worlds most valuable domain if it could actually deliver it's meaning might be say nextweekslotterywinningnumbers.com" or maybe a shorter version. If one wants to to be that optimistic, theoretical, existential, then yeah all of these 'theoreticals' could come into reality tomorrow, but don't hold your breath.
There must be a reason we don't see these domains topping domain sale records for a domain and searches?? So suppose the answer to worthiness of cancercure lies on a similar plane.
But lets say there is cure cancer tomorrow [breaking all known rules of science along the way as cures don't exist that's why no drug company describes anything as a 'cure', gov researchers do, actual drug companies don't, what they do is provide treatments that work on some people but never all] it's unlikely to add much value to your domain.
It's too big an idea, even a dotcom couldn't corner it. The cure would be given a branded name not a generic one leaving cancercure as one of probably millions of domains and websites trying to earn a few quid off the affiliate scheme assuming one was available which there wouldn't be because as the first medical cure in human history, why would they need affiliates???.They wouldn't even need to advertise. You would have waited all that time, possibly years just to be like a derivative payday loan affiliate page.
So lets say you battled past all that, then you've only got your morality to consider.