What made bitcoin survive is that it is decentralized. There is no central point which can be attacked and shut down.
Past attempts to create a digital currency all failed because they were not decentralized and/or because they couldn't solve double spending.
Nicely said. Good to see some lessons from the past history of cryptocurrency. Right now, when we talk about cryptocurrency the standard is of course Bitcoin and anything that is centralized like the newcomer Libra or even the Ripple we usually can say that those are not at par and should not be compared with Bitcoin with some even saying that those are not cryptocurrencies at all.
they ARE cryptocurrencies by definition because the definition of a crypto-currency is a currency that is based on "crypto-graphy", in that definition there is no talk of decentralization. we add that later because the original (biggest) thing we all know is bitcoin and it is decentralized.
the coins such as Libra, XRP, BCH,... are bad because they are centralized and this technology is working best and is desirable as long as it is used decentralized.