He feels really secure

[keannu]

What does this "secure" mean? "comfortable" or "firm"?

46)The person who sees the best in me and brings it out is Chad Diamant. People say that Chad is a “really gorgeous guy,” and I can see why: He feels really secure within himself and makes others feel (e) depressed1. Chad has a special ability to see the “up” side of life. To him, the glass is never half-empty; it’s always half-full.

[Rover_KE]

I'd say comfortable or confident.

Rover