Hey, why do so many people and businesses rely on marketing? How do you does worth it to use every marketing tool?

You don't need to use every tool, as marketing tools can applied depend on situation and type of business. In my opinion you can at least try to learn about some of them. Like for example SMS marketing is used by many. I bet you've experienced when you get random SMS with services....that the thing. You can use to get people know you better and your services, this is how you will get more clients. So try to search and learn something about these tools. Good Luck