idealist vs insane person

according to thefreedictionary.com,

idealist:

1. One whose conduct is influenced by ideals that often conflict with practical considerations.
2. One who is unrealistic and impractical; a visionary.
3. An artist or writer whose work is imbued with idealism.
4. An adherent of any system of philosophical idealism.

insane:

adj.
1.
a. Of, exhibiting, or afflicted with insanity.
b. Characteristic of or associated with persons afflicted with insanity: an insane laugh; insane babbling.
c. Intended for use by such persons: an insane asylum.
2. Immoderate; wild: insane jealousy.
3. Very foolish; absurd: took insane risks behind the wheel.

absurd
adj.
1. Ridiculously incongruous or unreasonable. See Synonyms at foolish.
2. Of, relating to, or manifesting the view that there is no order or value in human life or in the universe.
3. Of or relating to absurdism or the absurd.

Somehow I feel that there's a gray area between being an idealist and being insane.
I THOUGHT i was an idealist, but I thought an idealist can still work realistically,coz what's the point of ebing idealist if you don't know that it can work out?

but,I'm surprised by the definition given by thefreedictionary.com,unrealistic and impractical?am I like that?or I'm just someone without vision that thinks BIG but no philosophy beyond??

am I too naive?
I always compare it to how my mom nvr said that studying in spore is impossible..
it was impossible for me..it looks like sth up there..
but God enabled me to achieve it..

so if even now many ppl say,we can't do this...
am I too insane to say that there's a way to achieve more than this??
why do we always see other people can do better than us but we are stuck here??
is it a mentality problem or am I just insane and unrealistic??