Using a device under particular circumstances might be unethical. I think it would be huge stretch to consider inventing and patenting a specific mechanism for an electric bike to be unethical.
In any case, the USPTO considers if something is useful, novel and non-obvious. The use of something might be illegal somewhere but a patent does not give one the ...
The premise of "3 * sales" is not correct. The treble damages for willful infringement is 3 times whatever it would have been otherwise. It is not always imposed.
Other than that, yes. Staying ignorant of possible patents out there is a very reasonable plan whether for software or for hardware.