Not yet, but I know that we are getting close where can claim that btc is the strongest currency. I can feel that we just need to take a few more steps before everyone around the world will use btc instead of usd. It may not be a quick transition but I know we will get there.
It is not the strongest in the world, besides it is not a currency, cause itsnot being regulated, rather its unregulated. Bitcoin is decentralized, thats why it cant be controlled by a particular countrys government, or be a countrys currency.
Bitcoin is just an asset meant for investment, and when compared to Gold in terms of being strong, Gold is stronger. Bitcoin is just more valuable than every other things, but fragile.