Don't worry if the bitcoin value will decrease because this is just a temporary. It will rise again so you need to wait. If you want to invest,then you can try some other altcoins, like Ripple.
Don't go for ripple, i recommend you to invest in other alt coins... Ripple is not fully decentralise like bitcoin and ethereum, so better to invest in other decentralised currencies.
Yes, ripple is not decentralized. However, it doesn't make it a bad investment. Perhaps, it makes xrp a traitor of crypto ideology, but that is not something everyone cares about nowadays. People stick to fiat. However, fiat has it's big problems like inflation, paper expenses, possibility of fake money or of not knowing how much money there really is.. That's why ripple can help replacing fiat. And especially because of it not being decentralized, government are more likely to choose it rather than other coins they can't control.