Wanting to be your own boss, or having the ability to freely travel the world are both a great “Why” to create the activation energy to take the risk and start. But in my experience, it’s rarely a strong enough motivator to help someone persist through 4+ years without any meaningful wins.
The strongest "Why" usually involves serving something other than yourself. For some founders I’ve invested in, it’s a specific group of people (e.g. patients with a particular disease), or protecting something specific about the natural environment. Those people I have seen tolerate extreme suffering - to the point that I have had to physically bite my tongue in conversations where I wanted to tell them to stop and give up (but I never did - better a cut tongue than adding my opinion/ego to their burden). Some of those founders ultimately failed, others found enough wins and are still going (and suffering), a tiny number experienced wild success.
So if you want to persist, then an interesting question is "Who" or "What" are you serving besides yourself?
A separate but related question is how long can your personal cash flow sustain this?
Good luck!