Then don't take any equity and ask for a higher salary instead (or, accept that it's not a time you want to be taking a risk on a startup, and look at a bigger company role). The founders should believe that equity has a lot of value, which means it's an important negotiating chip either way. If they don't, you might have a bigger problem

I find it hard to understand when people join startups where they don't have the conviction that the equity will be worth anything. Although there is always a high chance of failure, you should at least be playing with odds you believe in

Well I am selling pick axes as my time and skills. If you believe there is gold in the river upstream why do I have to bet on it ? If you really want employees to believe in your mission , you are looking for founders not employees.