What are the challenges of freemium?

As a seasoned professional in the realm of cryptocurrency and finance, I must inquire: What are the primary challenges that freemium models encounter in our industry? Do they struggle with user retention and conversion rates, or do they face difficulties in balancing the quality of their free offerings with the value of their premium services? Moreover, how do they navigate the delicate balance of encouraging users to upgrade while simultaneously maintaining a robust user base through their free tier? I'm eager to understand the intricacies and obstacles that freemium strategies encounter within the dynamic landscape of cryptocurrency and finance.