How much ETH is a good realistic target?

Is 1 ETH enough to grow into a nice nest egg in 20 years? 5+? 10 or more?

ETH is still not extremely cost prohibitive to accumulate, but I think that it will become much harder in the next year. What do people here feel is a good target for someone in their early 30s to strive for very aggressively?

Thoughts?