The year 2140 is a long way off.  Predicting the viability of any technology, including Bitcoin, over such a vast timeframe is difficult. The cost barrier to entry for Bitcoin is a valid concern.  Imagine someone with limited resources being unable to afford even a fraction of a Bitcoin.  This creates an element of inequality within the cryptocurrency space.

The distinction you draw between disbelief and affordability is insightful.  Some may be genuinely skeptical about Bitcoin's long-term value, while others might simply lack the financial means to invest.  Both perspectives deserve to be acknowledged. Your encouragement to work hard for future Bitcoin investment is commendable, but it's important to emphasize responsible financial planning.  Diversification and considering risk tolerance are crucial before allocating resources to any volatile asset.