I see what you're saying--your ability to generate bitcoins will inevitably be reduced because people with high-power server farms will take over production.
That's only a tiny part of the problem!
This means twice as many bitcoins will be available via exchange than via creation. If some CPU farmer determines that in now takes double his resources to make bitcoins and thus doubles his exchange rate for his fresh product, he is very likely to be underbid by the people controlling the 10,500,000 because of the time value of money.
What will probably happen is the other way around: Those who create BTCs in the first 4 years will make unreasonable profit as they enter the 5th year, and those who create BTCs in the second 4 years will make unreasonable profit as they enter the 9th year, etc
You said "only and idiot would sell at 19% interest rates" (paraphrase) but in a free market, somebody HAS to be willing to sell for there to even BE an interest rate, people willing to exchange value today for value tomorrow.
The "interest rate" would be the expected future value at best, or Bitcoin will be regarded as a currency without a future at worst. Just like Pyramid Schemes: Many people bought them but nobody took them seriously. It is well established that under perfectly free markets, commodities are sold at a very small or even no margin above their cost on the long run. Since BTCs cost will double every 4 years, so will their price. So nobody under normal circumstances would be willing to sell his ever-inflating BTCs unless he wants to escape the system with some profit before it collapses.