Only one factor - whether you can sell it for profit
Your question is too general. No one can tell you all the strategies involved in domain acquisition, everyone is different. Even if they could, 99% of the strategies may not work for YOU. Take some time and read the forums, then make up your own mind about how YOU will start/continue on your domaining journey. Learn for yourself, figure out what works for YOU. Good luck.
you should change the question, to,
"why end user spend thousands of dollar just for $10 domain ?:
is there any logic reason why they should spend $XX.XXX just for a domain
but since your question to general, here's my answer
most people will buy a profitable product after all who want loss am I right ?