There is no 100% guarantee in any investment because there are some unforseen circumstances that can affect your investment making you not to achieve the required profit. However as a Bitcoin investor to increase the hope of making profit for long term start by protecting your investment, let your portfolio be well protected, because once your portfolio is vulnerable, you are going to loose your investment. Besides Bitcoin is very volatile , and monitoring the price movement of your Bitcoin on regular intervals can trigger emotions making you to take drastic action that can make you sell your asset. So there are many things things that can make one not to make good profit in cryptocurrency investment, and when those areas are well protected making profit becomes something acheivable.
Like you said, anything can happen that we don't expect. So the best we can do is protect what we have control over. Securing our portfolio is number one, because if your wallet is not safe, you lose everything before profit even comes. And that point about volatility is very important. Many people lose money not because Bitcoin failed, but because they were checking price too much. You check every hour, you get emotional, you panic sell. That's how loss happens.
So I agree with you. if we protect our investment well, avoid emotional decisions, and focus on long term instead of daily price, making profit becomes more achievable, even though not guaranteed.