16GB is plenty. 64GB is a waste.

No. Not unless you’re running a data center or hosting a hundred players.

For 10 players with 50 mods, 8GB to 16GB is the sweet spot. Most popular modpacks will run comfortably on 6GB–8GB for a small group. Even a heavy pack like ATM9 or Create-based mods will be fine on 12–16GB. 64GB is overkill and just burns money on your server bill—or ties up RAM you could use for other things.

The real bottleneck for a Minecraft server is usually CPU single-core performance and garbage collection tuning, not raw RAM. Throwing more RAM at it can actually make performance worse if Java’s garbage collector has to sweep through a giant heap. Stick with 16GB, allocate maybe 10–12GB to the server JVM, and see how it goes. If you hit RAM limits, you’ll know—but you won’t.

Save the 64GB for a database server or a video editing rig. This is not that.