Thin ends is what happens when split ends have come and gone.
A strand splits and as the split rides up the strands one side of it tapers off and breaks off leaving part of a strand. Since your hair strands go through the same trauma together (They get brushed, exposed to harsh products, to heat...all at the same time), it's reasonable to assume that splits happen to them all at the same time, not that some somehow escape while some vulnerable little helpless fools just stand out and let damage happen to them. So while you're busy babying your hair (or thinking you are), nature takes place and the old wither away and fall away and you only become aware of it when your ends are thin.
Holding onto them isn't going to help anything, because partial strands are not as strong as full strands so in time they'll break off on their own and your retention will suck or you'll be like those women with long hair that tapers into something gross that reminds you of a rat's tail.
The way to prevent that is to dust regularly, so you cut off the start of splits (which are inevitable BTW) and therefore leave a nice full strand end; moisturize and then seal the ends with something heavy and that prevent moisture loss; style your hair in ways that keeps your ends hidden from the drying air and away from clothes that would rub the ends to death.
Don't listen to anyone who tells you to look at your ends coz you can't possibly look at all strands and if you can see the splits, they're probably too far gone...and if you're trimming one at a time, by the time you get to the last ones the split will be long gone and you'll swear it's not a split. Well then good luck while you hold onto skinny post-split ends.
ETA: I'll try to find a few splits in my hair today (I'll redo a few braids, and also strands that have thinned so you can see what I mean about it being a waste of time. You'll also notice that you need a magnifying glass to see some splits, so it's better to just dust all regularly (while they are still in that "unseen stage unless using a magnifying glass")) so that you never have to deal with thin ends.