With all of the choice on the market one tends to shop for the lowest price. Most of the time this sets the product up for failure as the lowest price isn't always the best product.
A knife is a tool, and as any trades person can attest to you're sometimes only as good as the tools you use. Most cheaper knives on the market are made from low quality steel. Such steel is likely to break under hard use, and with knives being the type of tools that people rely on with their lives a broken knife can cause injury or be the difference between life and death.
A sharp knife is a safe knife. The ability to hold a sharp edge makes a knife safe to the user and those around them. When using the edge of a knife to cut you want to get through the material with as little force as possible to avoid the knife jumping out once the cut is complete and possibly causing harm to the user or bystander. Good knives should hold an edge with minimal maintenance and be able to hold that edge through hard use.
Good knives can put up with hard use. The other tools a good knife can replace include but aren't limited to; hammer, baton, shovel, can opener, pry bar, glass breaker, saw, cleaver, hatchet, and more. Most of the tasks associated with those tools are very hard on a knife and can cause lower quality blades to break with the possibility of injury (or worse) to the user or bystanders. Good knives can and do get used as these tools everyday.
Good knives can be used and handed down for generations. Yes you can take a good quality knife and use it hard even if it does cost more than a lower quality knife. Don't let the price deter you from using it for what it was designed to do, in fact the price should encourage you that it is capable of the task in front of it as typically you get what you pay for in life. A good knife can take a lifetime of hard use and still be a family heirloom and a tool that lasts for generations. When measured in the generational lifetime of a true good knife the initial investment returns itself with dividends.