A quick search on Google will say this below on the purchasing power of dollar over decades
Since 1972, it has fallen by 99 percent against gold and lost 90 percent of purchasing power of real goods and services.
Imagine if US Dollar were a cryptocurrency, it would have been one of the most shitcoins ever.
This is just reminder that bitcoin is a paradigm that has lead the would to a new way of doing things, and a solution to both financial crisis of 2007/2008 and Double spending. It has proven to have performed even high than Gold in recent times and is probably going to be top #1 of all cryptocurrency for as long as it keeps existing.
Bitcoin is only a decade and five years old, the interest it has yeild and it's growth over the years both in price and community support has shown its uniqueness and should be taken as a serious investment. Don't trust a currency that depreciates over the years with your investment rather take advantage of bitcoin volatility today.
You can't compare USD to Bitcoin because one is a physical currency, printed and managed by the FED that's worldwide accepted and also a world reserve currency. Bitcoin is a virtual cryptocurrency with an innovation called blockchain technologies, is p2p, virtual and is based on absolutely different systems. Comparing the dollar to Bitcoin is comparing apples to oranges.
Bitcoin is also in limited quantity. There are trillions of dollars printed and in circulation around the world but there are only 19.8 million bitcoins mined where half of them are lost forever and we are left with even fewer coins.
It's true that the dollar and Bitcoin are fundamentally different, but this comparison can also be instructive. The dollar is a traditional currency, but it is subject to inflation and the monetary policy of the Fed. On the other hand, Bitcoin, while limited in supply, is also subject to its own volatility and risks such as hacks or regulation. Claiming that Bitcoin is a hedge against inflation is debatable, as its history shows strong price fluctuations. Therefore, it is essential to consider not only the differences but also the economic implications of each.