I like the coin but 4 billion max supply

That amount of coins will be mined over 130 years.
To provide some perspective, in 130 years time, when MUE has a coin circulation of 4 bill coins, it will still have about only 10% of the CURRENT total supply of Ripple.
Ripple, the coin which currently has a marketcap of nearly quarter a billion dollars & daily volume of over $3m dollars.
Does that ease your concerns at all?
The value in MUE will not be derived from scarcity, but instead from utility and natural growth from adoption. Those things provide stability and sustainability.