Delta SkyMiles are famously sucky in terms of overall value; for example, it’ll cost you 120,000 miles in business class each way between the US and Japan using SkyMiles (vs. say, 60,000 miles on Alaska). I don’t talk about SkyMiles much for that very reason, nor do I think you should hoard them. However, for domestic and short haul international travel they’re worth a floor of 1.127 cents per mile, and sometimes more when there are award sales. Delta lets you buy essentially any domestic or short haul international ticket with miles, so you’re not really fighting award availability in those cases either.
Take the above, and consider that currently it’s possible to get a Delta Reserve American Express card with a 125,000 mile bonus using this link (I stripped away any affiliate information so it’s completely clean, no one is going to get a commission with it.) Note: The link is subject to the American Express random number generator, so you may have to go incognito, try a different browser, and/or connect to a VPN. In my experiments, I was able to see it in Safari Private mode on the first try, and it didn’t come up in Brave’s Incognito mode in the first try. You can also try searching Google, Baidu, Bing, and Yahoo for “delta credit card” and clicking on a few of the resulting links.
Where am I going with all of this? The Delta Reserve card has a $550 annual fee, and you’ll earn 125,000 miles as a sign-up bonus after meeting minimum spend. That means you’re spending $550 for 125,000 miles * 1.16 cents per mile, or a total of $1,408 in Delta tickets for $550 out of pocket, which works out to a 61% discount on travel on Delta. As JustinV loves to say, America loves math.
Keep in mind that American Express has a 5-ish credit card limit (and a 10-ish charge card limit). Hint: The “ish” comes into play due to shenanigans.