We should believe this because there is no evidence that the factors that lead to globalization are likely to go away.
The major factor that leads to globalization is interconnectedness. We are connected both physically (through things like airplanes and cheap and easy shipping) and in terms of the ability to communicate (through the internet and telephones). This interconnectedness makes it easy for people in different countries to do business with one another.
For globalization to die off, these factors would have to disappear. There is no reason to think that they will. If they do not, global demand for material goods will continue to drive globalization.
Thank you for putting it into such simple terms..