As long as you have between 20 - 30 buy ins, there isn't much of a risk.
E.g. On a £2.5/5 table - the max buy in is £500. You should have at least £10,000 in your poker account before you play that type of blind level.
I agree with your idea of rebuying in tournaments, though. Cash rebuying is quite different, however.
What we're talking about here is a semantics mismatch - You're talkiing about "sanitised" Internet Poker ? where you pre-determine the amount of your "downside" - whereas my "pure cash" remarks were directed at "live poker" = I thought my references to Brunson & Livermore would have made that clear.
My hope is to "graduate to live poker tourneys" with access to big money. & my "fear" of cash Poker stems from a historical event where my great grandfather lost a Velvet factory playing poker.
Developing a "confidence" in "No limit" cash games would put me at risk of being tempted into Live cash games, with a risk of repeating history - Especially in view of what I wrote initially with regard to "Sunspot moments" If you can limit yourself to these tiny "cash" games on the Internet (Scalping) - then you may well be right BUT for myself - I couldn't guarantee that
"Rebuys" - Again we're talking of different situations - my tourneys - your "Getting stopped out" in "No Limit" cash - We don't really have an issue here "to get our teeth into" either I can't argue with "rebuys" in that situation because you're going to "Start again" (New trade) - although I'd go for a walk or make a brew or something to give myself "Closure" rather than just getting Straight back in, with the possibility that the "bad beat" would still have me partly "on tilt"