All cryptocurrencies are about network effect. The more people involved in the currency the more effective it is as a currency. The demand for cryptocurrencies is so strong that even with 10% or more inflation paid to miners they grow.

The effects you are concerned about here do not apply until the system reaches "peak value". The steady state involves everyone contributing new value proportional to their stake. This means that if I have $100 of Steem Power, then I must contribute $10 worth of value per year.

Steem isn't about "payments" so much as it is about "recognition of contribution". The pie of contribution is designed to grow at 10% per year. If the value of new contributions is less than 10% of the market cap, then the market cap will fall. If the value is greater then it will rise. In other words, the steady state of Steem is where 10% of the market cap equals the value of the contributions made each year.

Passive investors in Steem are betting that the value of contributions will exceed the 10% per year fee for lack of participation. Eventually most Steem will end up in the hands of active users who contribute proportional to their stake. Those who contribute more relative to their stake will profit from those who contribute less relative to their stake.

In other words, Steem prevents "rent seekers" and encourages people to provide real value to one another. Payment is made in the form of quality content and curation.