D500 costs about what the D750 costs. I'm downgrading for 3 key reasons:
1) To get some spending cash net of the switch (to afford a Macbook Pro)
2) To carry around lighter equipment
3) To carry around less expensive equipment
For #3, you could get insurance on your equipment, or maybe just not worry about it. If you want the quality that your equipment gives you, and you want to take photos, the risk is just something you have to accept. Getting insurance could mitigate that somewhat, though maybe that is in conflict with your desire to save money.
If you do decide to downgrade to an APS-C, as someone else suggested, the 7100 has worse low-light capability than say the 7000, if that is important to you (though there is a difference in resolution). It kind of depends on what type of photography you do and what your requirements are.
For the lighter equipment, what about using a prime lens like your 50mm to reduce to total weight you're carrying?
If you want to change systems but keep a DSLR, I suggest Pentax, as their cameras are usually smaller and lighter and the lower-end bodies often include more higher-end features than the comparable systems from other brands.