I would put it differently: it is often easier to agitate people to be against something than convincing them of the good of something.
In a democracy, politicians need a power base made up of followers (future voters). The more, the better. And when the right conditions meet, sowing a seed of destructive opposition leads to a plentiful harvest of loyal voters.
Why people fall for this mostly nationalistic rhetoric that opposes the EU is quite complex. I don't think that I have a good enough picture of that to say more about it.
For political structures the NIH syndrome isn't as innocuous as for software, you can't have a powerful political organisation without a powerful mandate, if people feel like they didn't have much of a say in the creation and functioning of a political structure you can be certain they will want to tear it down and build it from scratch.
In a democracy, politicians need a power base made up of followers (future voters). The more, the better. And when the right conditions meet, sowing a seed of destructive opposition leads to a plentiful harvest of loyal voters.
Why people fall for this mostly nationalistic rhetoric that opposes the EU is quite complex. I don't think that I have a good enough picture of that to say more about it.