*Ahem*. I hope that Phillwilk saw my reply. It has been buried in discussion which, albeit interesting, does not answer OP’s questions (and is far above OP’s technical level).
Thus far, halfway down page 3, this is the only post which addresses the substance of OP:
Everyone got sidetracked with the fun game of cracking keys that were purposely created to be insecure. Nobody answered the essential substance of OP’s questions.
From an inexpert position, Phillwilk politely and intelligently some important questions about Bitcoin’s security. He is completely incorrect in some of his basic assumptions; his questions should be answered!
[...]
The money quote:
Feel free to correct any of the above points but if the above is correct; can anyone answer the following;
* Address reuse was extremely common in the early days and there are several addresses with 1000+ BTC balances with outgoing transactions revealing the public key.
Why has this not been used to steal the funds?
Smart question. The answer:
Revealing the public key causes no meaningful loss of security.I'm sure there is a limiting factor to this method but I could do with it being spelled out in layman's terms.
The limiting factor is Pollard’s kangaroos will need to jump around for trillions of years to crack a securely generated key. Pollard’s kangaroos are “fast” insofar as they are
faster than other methods, which would take even longer.
Pollard’s kangaroos are fun. But please, let us not be so caught up in that as to get less-technical users unnecessarily worried about Bitcoin’s security.
Bitcoin’s public keys are secure. Pollard’s kangaroo method cannot be used to crack a securely generated Bitcoin key.