If this is such a systemic problem that it alters elections, the problem is with the system.
The individuals are doing a risk/benefit assessment at a micro level. It is more damaging for them to have a conservative government than it is for them to have a liberal government and that may weigh more to them than the incredibly slim possibility of having an ndp government.
You cant penalize people for picking what is in their best interest. And they can still be pissed off that the best choice they had still led to a shitty outcome.
If you want something different, the system needs to change.