I'm not really sure. I can't be 100% unless I find my self in the said situations.
That said, probably yes.
Also, there is another question, or better to say 2. If I say no, will the button still exist and give the chance to someone else? Will the button vanish when someone (me or someone else) pushes it?
If the answer for both question is yes, then yes, I would press is 100%.
2 reasons.
1. My "perfect" life would be a life where I would have a huge, positive impact on humanity.
2. If I don't press it, someone else will press it for sure. That someone's "perfect" life could have a huge negative impact on humanity.
Also, the definition of what we get from pushing the button is to vague. Needs more clarification. Is the "best life ever" defined by the person pushing the button or by the button. Someone's "best life ever" could include all his wishes coming true. Or someones best life could be "the best life ever" + "those 5 people will survive".