I think we ignore something when we consider that the limited amount of BTC will bring deflation.It is true that the amount of BTC is limited,but limited amount will definitely cause deflation? Of course the amount of BTC will reduce and never increase because someone often lost some BTC.
For example to explain why bitcoin will never bring deflation:
The value of BTC is always there when traditional currencies still exist,no matter how much the market price of BTC is.If the price of a computer is $1000 and the market price of a BTC is also $1000, we never lost or earn any extra money if we buy the computer with dollars or BTC,there is no different.
Consumer will prefer to own bitcoin.Why?As it is more convenience to pay with bitcoin,especially purchase something on the websites of other countries.
Will bitcoin become an investment whose price will be always raising?The answer is no.There is nothing keeping raising in the world.