Bitcoin supports decentralised finance without a trusted thirst party. That is in itself useful, and no other finance instrument can provide that.
for now it is true what you say in your opinion it all happened because there are still not many countries that recognize crypto as a valid currency or legality of all countries and if the crypto currency is acceptable to all countries it will certainly boost the economy both
There are so many chances for the crypto currencies that it will to boost the economy as usage of crypto is making the life of people is now getting good. We can take part in making investing and buying coins at low price. Its bad if countries are not accepting it they all should accept it and promote the use of crypto it can make our economical life so good.
This doesn't look to be a threat to the economy, this has helped with an additional money circulation which boost the economy. Whatever might be, the increase in the circulation gets reflected on the growth. Same as people giving importance to real life investment on securities, bonds, properties, shares, stocks, forex, now the trend has moved to the technology backed cryptocurrency. We can't say blankly that bitcoin doesn't have any practical usage. If it hasn't got any, this could've never reached such a level of growth in ten years of time.