In 2020, Solana was priced at less than $1. Since then, it has increased by over 70,000%. Some early buyers did become millionaires.
Today, Solana is already worth over $150. For it to increase 100 times from here, it would have to reach $15,000 per coin. That would give Solana a total market value of over $7 trillion, which is more than the total value of all cryptocurrencies combined today. This scenario is highly unlikely, though not impossible, over a very long term.
Ethereum, on the other hand, might not offer as extreme returns, but it is seen as a safer investment. If Ethereum grows steadily and gains more acceptance through ETFs and real-world usage, its value could increase several times over the next few years.