Well, we could put it this way:

If you're a genius, you wouldn't be posting here; that's for sure.
For example, when Einstein produced his theory of relativity, only 4 or 5 people in the
world understood the concepts he concluded accurately.

If you were a different and more intelligent life form you wouldn't be posting here,
either,(for obvious reasons-intelligence, capacity for newer and unknown theories, etc.
risk of capture for research purposes by governments wanting to be first to obtain
extra-terrestrial knowledge, etc.) so that leaves:

1. Delusional, meaning that you're not seeing things correctly; it's a personal mistake
in perception.

2. Bizarre means that something is strange to anyone who might see it who is not
under a mental condition that could cause delusion. The general public would recognize something bizarre. If you were delusional and pointed out something bizarre to you,
the general public would understand you to be "off your rocker", as in slang for delusional.

This is layman's understanding, of course.

Grandiose relates to false assumptions about oneself having great prestige,
exorbitant wealth, abundance of authority and power, far beyond the potential of even
the most extraordinary people of any time. ( I think a slang term for that would be "someone
is just out of it".)