Satoshi Nakamoto, a genius, of course, did not create bitcoin solely for this. Just like anything else that is neither bad nor good, it is how people use it that taints its reputation. Our current fiat currencies were invented for commercial purposes but some crooked-minded people use them for some bad activities. As such, you cannot blame bitcoin or any fiat currencies.
Sometimes I wonder how would I inform everyone in this forum that bitcoin is nothing compared to how much fiat money is being used in illegal transactions. Okay, bitcoin gives you anonymity privileges. But that doesn't surpass the amount of money that have transacted for illegal activities in fiat.
Just like bitcoin, a gun wasn't made for the sole purpose of killing innocent people. Yet here we are. We have terrorist attacks almost everyday. Electricity was discovered and the discoverer thought it will be very useful for machines and whatnot. Yet we have an electric chair which kills people. A lot of things are being used for things that are different than the creator's objectives.