You're making a lot of false assumptions. You could be the owner of gun, intending to fire it against inanimate objects only. Like a paper target at the gun range.
One could even have bought it out of simple curiosity.
Yes. And you could be a member of Ashley Madison who's just curious, or who's doing a documentary for Al Jazeera, or who's trying to see if your spouse is on it.
I was speaking generally. I said that it's reason/evidence in favour of a conclusion. I said that it isn't proof of it. Those kinds of general rules and presumptions are useful for all kinds of things and in all kinds of ways. Or do you think that our judgements should be entirely composed of perfectly comprehensive and universal rules?
One could even have bought it out of simple curiosity.