A few random thoughts:
1. Assuming you can afford the toys you want, and that you really want them, go for it. There's no reason why only professionals should have them. Are there any other hobbies where people keep saying, implicitly or explicitly, that you shouldn't get the best equipment unless you plan to make money from it? I would forget about that line of argument.
2. Lenses vs bodies. It depends on what you have and what difference it would make to the sorts of photos you take. For instance, if you like taking photos in situations where high ISOs are unavoidable and your body has a crop sensor and you have some good lenses, it would make more sense to me to upgrade the body to FF rather than buy more lenses.
3. Following from 2, you have a marvelous camera body already, which may tilt the balance back to lenses. You seem to be in the US, in which case it's easy to rent photo equipment. So why not rent a 1DX and find out for yourself whether "general overall IQ" is noticeably better, whether high ISO performance is noticeably better, whether face recognition really works, and whether higher FPS makes a difference to your life?
4. If your interest in new toys is merely to improve how the photos you take look, or to enable you to take photos you can't take well with the equipment you have, rather than for the sheer fun of playing with new toys, take a look at your portfolio and ask yourself what you wish was different in your photos. They may well be features - composition, light, etc. - which won't be affected in any way by changing your equipment.