Here is a simple explanation, although a better answer is needed.
I think that enveloped viruses are less tolerant because they are too sensitive to ambiental conditions, such as solvents, acids (e.g. they cannot survive for a long period in gastrointestinal tract), dryness, surfactants and so on. It's something related with the coating of these viruses.
I've learnt that, for the above reason, enveloped viruses can only survive under special conditions ("wet conditions") and they are generally transmitted in "wet" body fluids, like blood or respiratory droplets.
Naked viruses can survive under harsh conditions.
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