Investing on Bitcoin is the best think to do if you cant decide on what else to buy. I think bitcoin will be trillion dollars market cap in less than a decade. Any opinion?

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If you can't decide what else to buy then yes bitcoin is a good bet but a trillion dollar market is unlikely, there is no indication that the average person will ever want to use bitcoin. The features we love about it, ie privacy and irreversibility are exactly the reason why the average person doesn't want it.
What do you mean there is no an indication for those person to buy or use bitcoin?
OP, bitcoin will still be the king. BCC has the same future with ETC. that's just another clone from bitcoin. it doesn't make sense the original get passed by the fork coin such as BCC.
But it will too far from the market cap will worth trillion dollar.