Actually after checking your question out, I was thinking you will make it more explicit in the blog post but to my surprise you stated that you want to present it in a University.
I gave your question deep thought after reading through because one of the purpose of buying goods is mainly for consumption purpose and other beneficial uses profitable to man.
There are different types of goods which can either be consumed by man or non consumable. Goods that can be consumed by man maybe be perishable or non perishable depending their lifespan.
If I am to answer your question, I will consider goods that can be consumed and not goods that can be used for other activities.
Why do people consume goods?
I think we actually consume goods for the following reasons.
1) FEEDING PURPOSE : As humans, one of the great reasons we buy goods is mainly for consumption purpose. We need some consumable goods to keep the body in good condition and good health state. Without eating, we won't be able to carry out our daily activities just like I am answering your question presently.
In summary, people consume goods for the purpose of feeding themselves so that they can do their regular activities or tasks.
2) TO AVOID WASTAGE OF PERISHABLE GOODS: One of the best ways to avoid wastage of goods with low life span is to consume them. Sometimes, there is limit to the amount of days some goods can use and this is why storing some goods may not be advisable. The best way to avoid such goods wastage is to consume them.
Rapid consumption of goods with low life span helps to decrease or reduce the chances of goods wastage.
3) TESTING OF NEW PRODUCTS : This is something natural to everyone. As humans, we will always be eager or curious to taste or test new things. This is why most people can't do without going for new product or latest products most especially consumables goods. The best way we can test such goods is to consume them.
Those are the three points I think people consume goods and it is something everyone experiences.
Thanks for reading and I hope this helps.