that's the puzzle developer wants to see 
If now investors in bitcoin learn that a small bunch of intusiasts with the help of improvised means were able to find private keys in 100 bit space ,then what will happen to this whole story if it is seriously engaged in professionals with cool equipment and leading programmers.And I wonder how soon the cost of cryptocurrencies will cost $ 0.Currently not an issue for those that use proper secure random full entropy 256 bit private keys even if the attackers use "cool equipment and leading programmers".
These keys still have 128 bits of security even with the current search algorithms. The current record on this thread is 100 bits which leaves 128 - 50 = 78 bits of headroom.
Assuming 115 bits is possible then that still leaves 128 - 58 = 70 bits of headroom.
If you want your coins to be more secure than that then use a standard 160 bit Bitcoin address and never reuse your Bitcoin addresses.
If you want even more security then use a 256 bit Bitcoin address and never reuse your Bitcoin addresses.
Finally, if there is a breakthrough and ECDSA is deemed less secure then Bitcoin will simply switch to another algorithm with network consent - which I believe would happen given a known reduction in the security of the ECDSA (as long as the change did not try to sneak in a whole lot of extra baggage with it).