reckless means showing no regard for danger or consequences, so.... smoking could be reckless, or maybe drinking to excess.

but it's more than that isn't it?

in my experience it might come from this:

if you do have a sense of worthlessness then perhaps after a while you internalise this to such an extent that you are prepared to destroy that which is perceived as worthless, yourself, through reckless acts. you are also socialised as well. so if life-events have caused your imbalance rather than chemicals, you are conforming to your society. there seems to be quite a correlation between say, social-economic class and desease, mental and physical.

try this analogy: slaves in ancient rome had much shorter and more miserable lives than the patricians. and the injustice(?) might well have driven some slaves mad, which hastened the slaves' demise. the patricians couldn't care less, one less mouth to feed.

if you can, another society, environment might help. and, if at all possible, you've heard this before, try to think positive about yourself.