I have been studying the secp256k1 for the past 2 months, and tried at least 40-50 methods to figure out which one could be used to crack the target k by hand, not using automated existing tools.
Experts and mathematicians have been trying to crack elliptic curve cryptography ever since 1985 and they only have a handful of methods and haven't been able to make any meaningful progress. But good luck to you...
other coins copy pasted bitcoin's curve with a bit of modification, what is special about it?
Actually other coins that copy the ECC part of bitcoin, are creating an exact copy without any modification. The changes they make is elsewhere like the address encoding and PoW (eg. LTC, Doge, ETH) or they just replace the curve itself (eg. NIST P-256 in NEO).
What @ecdsa123 is doing has nothing to do with other coins though, they are just pointlessly manipulating the basics of the math behind the algorithm to sell a silly script to anybody who falls for it.