I'm firmly in the "credit card/tap to pay" camp, but still always have some cash handy when traveling - in the US or abroad. With the Euro, it's way simpler for us, since we can return later to another country that uses the Euro and just carry forward our cash. It get's a little muddier with somewhere like the UK where we visit less often, so I'd be more inclined to have less on hand than I do Euros.
As we just stash our leftover paper cash with our passports, it's relatively easy to comb through the cash prior to our next trip to see if we have any money leftover from a prior trip to bring with us. Sometimes (mainly for Euros), I also check our coin jar to see if any coins are in there as those often come in more handy than paper bills for things like a bathroom.
I also check on our bank's website for partner banks and their locations in the places we'll be visiting. I'll hit those ATMs up for a cash refresh if convenient.
But, in 2025, I find I return with pretty much all the cash I started with for most trips. Not an awful "problem" to have, but certainly a little bit of a "waste" - ie cash sitting in a file cabinet waiting to be used. Negligible in the big picture, irksome in a OCD-ish way. Since 10 Euros, 100 Euros, or 1,000 Euros take up about the same space, it's not an issue to have cash handy with out passports (in a moneybelt or hotel safe), and my wallet will always have some local cash too.