Why do we run out of internet so quickly?

[Holly]

We have 200gb of internet per month, but nearly every single month we use it all up. We end up using about 10gb per day on average, and we have no idea how we could use that much. there are 4 people in our family, and two of them barely use it, they use the internet on their phones, and they never run out when they get about 4gb per month on their phones. any ideas of what could be causing this and how we could fix it are much appreciated.
we know that youtube and watching movies uses a lot of data, but we know people who watch youtube more than us, and they barely use15 gb a month. we have called our providers, and they have provided no help, and their only suggestion was to get a bigger plan but I think 200gb is big enough.