For example, someone told me it's nonsense to hold btc and ltc, because ltc follows btc pumps/dips and I should only hold 1 of them.
Should I consider adding a privacy coin?
Or even more "platform" coins like eth?
You do what you believe will give you the best return. They can do what they want with their own money. Diversify and hedge wisely...however you interpret that. Good luck!