The opposition didn't feel rational. For example, the EPR paradox was presented as a failure of quantum mechanics, when quite the opposite was true - and indeed

The opposition didn't feel rational. For example, the EPR paradox was presented as a failure of quantum mechanics, when quite the opposite was true - and indeed quantum entanglement has been proposed for commercial applications. Simply put, in his later years people were already using QM to solve real world problems, while he was telling them their theories were wrong.