It Isn’t Better ‘There’ Than ‘Here’

I struggle with the concept that it isn’t better ‘there’ than ‘here’. If that is indeed true what would be the point in investing time and effort into something that isn’t better anyway? An example would be someone who wants to sculpt a muscular body (this isn’t my situation but just trying to find a clear analogy). Clearly that is going to take very significant time and energy and if the person achieves this and the outcome isn’t better anyway, that to me seems hopeless. I guess, I’m saying I don’t believe the concept to be true in any scenario I can construct. I think ‘be careful what you wish for’ is true but I think that is very different to ‘it’s not better there than here’. In every scenario I can think of where I have proactively changed my situation (built a business. Moved to another country. Improved my fitness) it absolutely IS better ‘there’ than ‘here’. I would love some guidance on what I am not understanding with this concept. Thank you in advance.