They are losing anyway the battle field is in their turf.Their factories, businesses farms are being destroyed and their livelihoods they built over generations is almost being wiped out.I just don't think it's a good idea for them to "surrender" because that would entail a program of suppression that could last indefinitely; putting yourself to the mercy of others is revolting and rarely ever results in real peace.
In addition to the many humiliations they would undoubtedly suffer, they would have to endure ccupation; the Amhara should push the Tigray out and make the war terrible for all involved, so that a negotiated settlement becomes the only viable option.
I also imagine that surrendering would be terribly emasculating; I can't see how Amhara women would still be attracted to their men if they surrendered -- leaving them open to the usual dishonours and miseries that follow. Best to burn everything.
By the end of the war their land will resemble Idbil.