I have some sigs. I just don't have time, and with kids, the inclination. And I don't buy them.
To me, value is in the eye of the beholder though. If someone wants to pay $75 for a Meninga 1990 then you have to be safe and secure in provenance. And players are suss to multi sigs on same cards now so it kind of spoils the fun a bit.
I don't buy IPs. I prefer to get my own but have traded a couple and have been gifted a couple more which I really appreciated.
I know and see a couple of regulars on here do their IPs and I admire their perseverance and collections. It's hard work. And they don't sell either, trade only.
So, for me, IPs are worthless unless in my PC.