Some people do have have anything than criticising what works good, but I do not blame then than their ignorance, because of not for ignorance they wouldn't be critisizing Bitcoin which is 100% open source and 100% decentralized while it is deflationary. They do not have to buy bitcoin like those that critizied Bitcoin in some years past and missed out on the bullrun periods.
3rd states that there were cases in which big pools had >50% compute power .. I do not think that we have any protection against that right now? Or not?
That is a big lie, but China as a country still control 65% of the mining power which is a way more higher in 2019 around 75%, this computing rate is gradually reducing as some other countries are joining to mine and as some miners are leaving China for better place to mine. Also know that computing power are not even centralized in China because they have different mining pools that are computing, not one.
Is there other solution to these problems other than splitting your crypto money to as many wallets and currencies possible?
Which problem exactly?
Bitcoin and its blockchain has been working successfully without no 51% attack since the creation of bitcoin, so what are you implying when there are many more decentralized mining power. Bitcoin is just the perfect money and asset with perfect blockchain , all you need to do is to keep your bitcoin safe, because if you Bitcoin is not safe, the fault is from you not bitcoin source code or blockchain Orr anything about bitcoin.