VXX is not an ETF, it’s an ETN which purchases near term vix futures and rolls them to later dates as they approach expiration. It increases in value when the short term vix futures it holds increase in value, not because investors are pulling money out of stocks to invest in VXX. The futures it holds increase in value because implied volatility (fear) increases during market downturns.
A quick look at a chart will show you that vxx tends to lose money in the long run. This is because longer dated vix futures almost always trade at a premium to short dates vix futures, so unless there is a major crisis, as expiration approaches the futures lose value, which makes buying vxx only suitable for hedging or short term speculation. Shorting vxx could theoretically make you money in the long run, but sooner or later there will be a crisis and a short position is likely to blow up.
Glad you said you aren’t planning to invest because VXX is an instrument that should only be touched by people who have a very strong understanding of what it is. Investing in it as a novice is a sure fire way to lose a lot of money.