A DSLR generally won’t quickly "wear out" just from being left in live view/video mode, but continuous operation does increase heat and power-related stress.

The main concerns are:

• sensor and internal heat from being powered continuously
• battery heat and drain, which is reduced by using a dummy battery/AC adapter
• autofocus motor wear if continuous AF is left running for long periods

Shutter wear is usually not the big issue here, since the shutter/mirror cycle happens when entering or leaving live view rather than continuously during live view itself.

In practice, long continuous DSLR use is common in things like astrophotography, where cameras run for hours at a time without problems. That suggests this kind of use is generally feasible. Heat is the most likely limiting factor, especially in warmer environments or if the camera body has poor ventilation.

So: it’s possible, but the main risk is thermal stress rather than immediate mechanical failure. If used this way, external power helps, and disabling continuous autofocus when not needed would reduce unnecessary lens motor activity.