Genuinely productive people are pretty rare (1 in 100 type numbers). I can't claim to know exactly what a debate opponent is thinking, but usually I assume:

1) Most people are more involved with the famous and common 'bullshit jobs' instead of the much fewer super-productive jobs - like a couple of farmers who can feed orders of magnitude more people than just themselves. Maybe they haven't interacted with the parts of the economy that do genuine wealth-creation and don't understand it.

2) They don't accept that incentives matter more than inherent nature, so they believe the productive will continue producing even if the incentives to do so are reduced, so resources can be redirected to 'those with needs'.

The second is a pretty defensible position, although obviously I disagree most of the explicit and implicit assumptions.

As an aside, this has already become one of my fastest down-voted comments. Could someone stop by and explain what they don't like about it? I didn't think it was very inflammatory.