Pre-order factors for me:
1) If I am physically able, I will play this game immediately on release. It's part of the fun for me.
2) If the game sucks, at least for my copy, I'll be out what would cost me a dinner for two. I ain't gonna sweat that, period.
3) I'd probably only regret it if I found out immediately after release that it flat out wouldn't run or crashed every couple of minutes....I consider that highly unlikely.
That's exactly why pre-ordering is useless : you could do the exact same thing without preordering.
And that's true for almost any listed pre-order "factors" I've found here.
There are only three possible legitimate reasons to pre-order a non-indie game :
1 - if it costs less than after release (but it's still risky). I can understand that.
2 - if it provides additional content that you can't get immediately after release (I won't debate why it's a bad market practice now).
In that case, experience tells me that pre-ordering is not worth the risk. If I want to play the game at release, I can as well buy it at release. If I really don't like it, I can now ask for a refund from Steam, while it's not alwas 100% guaranteed for a pre-order. If I bought a complete edition but I don't like the game... money wasted.
3 - if you can play earlier. I think it's the best reason to pre-order.
Pre-ordering the game just because you're a fan and want to show that is vain. Game companies have to know they need to offer something in exchange of our trust. Please, don't pre-order if none of these 3 reasons motivate you.
And in the case of Civ6, none of them seems valid, since there is no discount, no pre-release for pre-orderers, and it seems too risky to buy their -very costly - deluxe edition.