True. That is because the phrase is really a shorthand version of the Drake “Equation” which, in turn, is itself just a very high level approximation of an equation human beings don’t even know all the terms for at present.
Properly, it should be:
The Universe is so vast ... there MUST be life elsewhere.”
The “...” representing, of course, all the various circumstances necessary for life (however you care to define it) to develop.
This, in itself, is a far less stringent condition for success than requiring the development of a spacefaring civilization in our galaxy and its explorers reaching the Earth during a time when mankind exists and is sufficiently advanced in its own right to properly evaluate their arrival. That achievement, to start out with, requires the development of life (and its elaboration) in at least TWO places vice one.
No one can offer any real opposition to that opinion.
However, what are the odds that the life that must exist elsewhere would ever cross paths with life here on earth.
It is not sufficient that the two lives cross paths in physical location they must also cross paths at the same point in time.
In consideration of the vastness of empty space what are the odds that different forms of life cross paths in both space and time. Life that is one billion years ahead or behind another life or separated by billions of light years in distance may not recognize each other.