Bitcoin along with its Blockchain only serves as the foundation and is not meant to be the end to end solution
Think of Bitcoin as the heart which pumps blood throughout the entire body feeding all vital organs. Other Blockchains will act to lessen the stress put on Bitcoin, the heart, to more efficiently keep blood-pressure even throughout. The blood-vessels and capillaries represent altcoins, serving to carry important nutrients so as to sustain things, allowing the body to grow and flourish. All of these things are needed for the entire body to function properly.
In the end, everything feeds off of the heart, Bitcoin. Over the years, Bitcoin has gone through multiple stress tests proving its overall state by proving to be un-hackable.
Don’t underestimate the power and vital role that Bitcoin plays. Cryptocurrency as a whole can be likened to a world-class symphony born from the dream of futurist now becoming reality far beyond what they had ever imagined.