Bitcoin is the first cryptocurrency ever made and the first fork of a cryptocurrency protocol. It was the first to introduce the concept of encryption and decentralization of money. Since it was created in 2009, the protocol is now getting obsolete. The fact that about 150'000 transactions are unconfirmed is the evidence. Bitcoin cannot handle an high traffic of users, because most of the people are starting to have transactions not mined (and stuck) for days or weeks. If PoW already showed its negatives with the high energy cost, now the evidence arrives from the quality of service, when the traffic involves more people and the fees attached to transactions increase to get higher priority.
If the traffic would increase even more, with the current level of difficulty the entire system is doomed to burst. There are other cryptocurrecies that solve most of these problems. Bitcoin is now stronger than other cryptocurrencies because it was the first and it has a larger market capital and a larger user base. However, it doesn't mean that its concept is better and that it will survive in the future. In my opinion, Bitcoin will burst when the system will not be able to handle all the transactions. We can see the first symptoms right away. Check this website:
You can see with your eyes that the number of unconfirmed transactions is very high in this moment, and it will increase in the future with the increment of people making transactions. Most of the transactions are not mined because their fees are too low for the miners that are wasting computational power to get the best profit at the least expense. They wasted millions of dollars to create mining farms with powerful ASICs and graphics cards. They want to mine transactions with the higher fees to have a payback and make even more money. As nobody is interested in wasting an outstanding amount of power to mine transations that have lower fees than others, the transactions with lower fees are rejected until they will be eliminated and created again with higher fees, in an infinite loop of speculation that is creating a Transaction Fee Bubble. As you can see from the above chart, the transation fee average incremented from $0.27 to $27, 100 times in just one year. The fees are growing so fast that transactions will be not convenient anymore. People will migrate their money to less expensive currencies, where transactions will not get unconfirmed so easily. For instance, I'm started to do it right now because I had unconfirmed transactions and no decent way to accelerate them without paying mining pools or other fees. And If I'm doing it, I'm sure that in this moment there are other people that are making the same consideration. So, this is the reason why I believe that Bitcoin is doomed to burst in the future.
Bitcoin was born when crypto was just an experiment after the financial crisis of 2007–2008, when mining could be done with laptops and the traffic was order of magnitude lower than today. This is what made people that bought thousands of bitcoins in the past for few dollars filthy rich today, but this is also the reason why the system will collapse in the future. It won't be a surprise if one of these days we could hear the news that bitcoin bursted and all the money are lost, with the biggest waste of money and power in the history of humanity. What I'm saying is something that can actually happen if the protocol won't be capable of handling all the transactions, or if it has a bad quality of service at the point that people are not interested anymore. If transactions are getting unconfirmed already, the system is not suitable to buy anything. Imagine that you are buying a car in BTC, and a transaction of $40000 gets stuck for some reasons. In that case it could be mined by mining pools, but it is equally a waste of time considering that transactions with fiat today are done in the blink of an eye. Even worse, little amount of money cannot be mined easily if the fee is too low, and the fee cannot be higher if the amount is little. Just to make a pratical example, considering the huge amount of people that are struggling with unconfirmed transactions in this moment (including myself), I won't recommend bitcoin to buy even a toy of $30.
When the system will reach a point where shopping will be not suitable, the currency will die soon. I suspect that the only reason why the BTC currency is still alive is for the huge market capital and trading. When bitcoin will be abandoned because the service cannot handle the transactions with decent fees, it could happen that people will remove capitals very soon, and the bitcoin value will decrease to few dollars. Miners will not mine anymore, because the value is too low and it doesn't payback the machines bought for mining. All the hardware will be sold to repay the expenses, or just used to mine more convenient cryptocurrencies. There will be no miners and all the transactions will get stuck into the unconfirmed limbo until they will be erased by the system. The transactions won't work anymore even to move the money to other cryptocurrency and all the money will be lost forever (this is an extreme scenario but it could happen). People will lose millions or billions of dollars and if you have money, there is a good chance that it could happen to you, so make attention please and read the news, because everything from now on could happen.