GMing is generally harder than being a player, if only on the numbers. A player controls one character (for most systems) while a DM controls all the NPCs. Even if any one NPC is simpler than a PC, there is usually a LOT of them.

But to me, what really makes games harder is not gelling with the players. I'm a DM of a Discord D&D 5E game, and it just flows pretty well. Occasionally I need to kick the party in the tuckus to keep the game moving, but generally there's good back and forth, in roleplay, in combat, in all the gaming parts.

I find it much, much easier to be a GM in a group that I work well with than a player in a group that's not as good a fit for me.