If you will receive something from a thing then you would make effort to get it. In an Olympic, you will compete giving all your efforts and strength to get the gold medal as the reward if you emerged as the champion. Because of the legend that surrounds it and the mystery that was made for it to be a sought after thing, the Holy Grail is also a prize that many want to get. Becuase of the assumption that it can give eternal life.
This is because it was used to catch Jesus blood. Because of the popularity of it, many believed and now also want to search for it so that they can have it as the most prized possession and to be able also to receive the rumoured benefit of it. That is why many have claimed to have the Holy Grail and so many people visit there. You can see in the infographic the different theories and assumptions about the location of the true Holy Grail.
Because people look for things that are connected to Jesus they can even make this kind of stories. But because the apostles do not regard it as important why would we also try to find it? If it cannot give salvation why must you chase something? The faith that Jesus is looking for is the one that obeys His commandments and not the one who just look into things that have no value for salvation but only for wealth and power.