Currently BTC prices have been hovering at 6000, and if the BTC prices fell to $5000, $4000 should be not far off, the market is confirmed in the bear market, want to rise to $20000, you may need a couple of years. 
Your pesimistic forecast is not justified yet and most likely will not work. Bitcoin does not go down in its price. On the contrary, over the past month it has risen to the level of 8,200 dollars and, it seems, does not intend to fall deeply. Moreover, many experts predict its growth in the short term. Autumn is coming soon, but in this period bitcoin and other crypto currency are very active and always rise in price. We hope that this will happen this year.