When I am asked whether people have to discard their illusions to see the truth, I suggest to change the language of this question. Instead of truth vs illusion, try to use belief vs projection. Why? I find the latter juxtaposition more practical.
Both the truth and the illusion are beliefs, the difference being only the degree of confidence in their reflective power (yes, we use both to reflect the experienced or communicated reality). After I find a truth no longer fitting my world’s model and useless in achieving my objectives, I abandon it as a misrepresentation, a wrong concept, an illusion.
Projections are deliberate non-existent constructs, idealistic, fictional, imaginary objects which we intentionally and creatively develop to change the reality, for better or worse (it was the human mind that imagined and created the gas chambers for mass murder and ovens for baking banana breads). Projections are not true because they do not exist yet. But we hold them as representations of the modified reality we want to establish, we use them as blueprints.
So my answer to this reformatted question is “No”. Hold on to the beliefs that keep you sane and are practically applicable in the pursuit of whatever ends you have. Keep the projections as well because they are the ends you consciously set and pursue. If your subconscious or somebody else set your objectives, then you do not live your life.