If you have short term plans, bitcoin might be down when you will want to sell it, but if you can hold bitcoin for like 10 years, it’s not possible for you tell sell at loss if you will be selling it.
There's is no guarantee on what you're saying in the bolded part. Although Bitcoin is a very good investment and has a history of price appreciation, yet the price is not guaranteed to keep going up. For this reason you're advised to invest only from your discretionary income and not money meant for your survival so that in case it doesn't play out the way you are proclaiming, you can move on living a normal life. We all believe in Bitcoin prospects and we're casting a fair bet on securing our financial future in Bitcoin believing that it continues to perform well but for a guarantee, I'm sorry there's none