just googled it... oxford learners dictionary says both countable and uncountable... so i am guessing its uncountable if we are talking about how much money or time you invest, but countable in the amount of investment actions you do? not sure if it can have same meanings in vietnamese? and tbh its not my first language either. just was asking since with much i was counted wrong. btw i like the way you german no diggity :D
In that case, I think both can be right. In Vietnamese, there is not distinction between these two meaning.