It's not thinking too much, in that specific instance, that is the source of the problem at all.
The point (value or reason for) to the things they're claiming have no point, are provided by us, not the universe via magic assignment. That is the source of the mistake.
Pretending the value is externally assigned or innate is the source of the premise that there's no point to the big thing (existence, life, work and so on). In the process of being disappointed in the lack of innate value, they're actually mentally assigning low value to the thing in question (which is psychologically the entire point: it's about debasing the value of the thing, it's most likely a revealing indicator about the present state of mind).
For example: smart person thinks too much, they realize there's no point to life because we're going to die (or similar setup). The problem with that is, the point of life is decided by the smart person. They're in fact deciding to assign life less or little value in the act of saying there's no point, in that action they are actively determining the point: they're deciding there isn't much of one. They made a choice (with it being understood of course that a person may be in a mental place where for any number of reasons they can't clearly recognize a positive value to existence).
The old question: what is the point of life? Does in fact have a very obvious and very simple answer: you decide (which simultaneously does not guarantee good results, even if you decide what it means to you or what the point of your life is to be).