BTC
Binance Coin - https://coinpaper.io/coin/bnb-binance-coin
Iota - https://coinpaper.io/coin/miota-iota
Nano - https://coinpaper.io/coin/nano-nano
All three have excellent development stats and are known in the community.
Binance Coin is super strong with Binance as a strong Exchange.

Made and lost the most money from Nano when it was called Raiblocks

Ripple has been holding more than 50% of the total supply of Ripple XRP tokens for a long time and thus can control the validation processes on the network. In December 2018, a detrimental story was uncovered by an independent researcher, Geoff Goldberg. According to the irrefutable evidence unearthed, it was alleged at some point that Ripple was using fake social media bots to lure the new users into developing an interest in the Ripple network. This greatly damaged the reputation of the institute and further raised questions about the integrity of the technology. This is what we might have seen with the XRP pump & dump in the last few days.
On https://coinpaper.io are a lot more metrics about a project's scandals/highlights to see: https://coinpaper.io/coin/xrp-xrp

IOTA gets roughly 300 to 1000 commits (code-updates) per month. The project is very active. On coinpaper.io are a lot more metrics about a project's progress to see: https://coinpaper.io/coin/miota-iota

One problem is that only a few people with a lot of liquid assets have the possibility to influence the Bitcoin price significantly. It is difficult to guess in which direction these trades are going.

Hodling the coins is a good decision. You can lose 100% of your investment at most, but you can win over 100%.

If you are able to constantly estimate the market with >50% probability, then you can make a profit on average every day. The only problem here is that days run differently well and it is very difficult to predict the market accurately.
Trend Analysis can help you, but is no guarantee. Trading bots are usually no guarantee either.

To be more specific. Immediately after the price drop seen in the candle before, futures up to $323 were bought in the timeframe of the next candle (here 1d).
A possibility here might have been that someone made a missclick with a big lever and ordered $323 instead of $32.3. As the market price remained much lower, the futures price fell back to the lower value.

Thank you very much for your opinions.
In any case, it does not appear that the fall in oil prices had an immediate negative effect on Bitcoin.

I hodl some specific coins according to the development of their products and with about 1 - 10% I like to take a higher risk with leverage.

What implications could the oil price drop on the mid-term bitcoin price have?

Do you think it is more likely that investors will switch to Bitcoin, or do you think it could be that the money is flowing out of the crypto world due to the uncertainty in the markets? Could it possibly have no effect at all on the Bitcoin course?

As all the other suggestions, I'd advise you not to partake in a pumping group. The only reason to check one out should be to get an insight on why a coin might be pumping after they signalled it. Do not buy into these coins as the users of the pump group will probably sell them within hours and leave you at a loss.

People will need some time. Noone wants to withdraw their crypto investments first. Many people will wait to withdraw their money until they have to. This might be the case for some this month.