It's still true that "clouds" cost much more than proper internet connections at DCs. E.g. AWS wants you to pay $90/TB, Hetzner $1.50/TB, a good deal on a contract is probably half what Hetzner pays since they need profit too.

And if you have two specific endpoints you need to transfer data between at a high rate, you can get stupidly cheap cost per GB on a leased line in exchange for making all that commitment upfront.