The main reason why people are investing their money is because they see it as an asset. They want to make money like the way they are doing when investing in other financial markets. If the price of Bitcoin is not volatile, people will not want to invest in Bitcoin and the adoption must have reduced not up to what we are seeing now. Since the price of Bitcoin is always going up and down, this has influenced the price of Bitcoin making it easy to trade and invest due to changes in the price.
More specifically, it's easy to resell after purchase, which is why so many new investors have emerged because they've already gained confidence in Bitcoin. Those new to Bitcoin can also learn about the unique methods used by veteran investors who are still very happy to hold Bitcoin, so that new investors can immediately eliminate any worries about holding Bitcoin. While Bitcoin's price fluctuations have indeed influenced most people to view Bitcoin as an opportunity in their lives, investors who already believe in Bitcoin typically buy more frequently, regardless of whether the price is falling or rising, because their goal is to hold and accumulate more Bitcoin each month.
You have brought up a critical issue of volatility as a risk and a catalyst to the development of Bitcoin. The price fluctuations that emerge around Bitcoin attract many investors especially due to the fact that such opportunities do not exist in more stable investments. Such volatility has made Bitcoin very liquid and easy to trade which of course invites new players to the markets. With time, when individuals acquire experience, most of them change to a more conviction-based trading nature than a short-term trading one. The long-term believers do not pay much attention to the movements of prices in the day and more so, to accumulation, purchase both declining and advancing markets. This combination of traders and long-term holders may still help in adoption, liquidity and general maturity of the market in the next decade.