Thanks a lot, guys, for your candid responses!
@LavrentLo, you nailed right on the head talking about not knowing what to spend on, hence hoarding them all. That is exactly I am with the gems. That's why I am posing the poll. Also I hope this will help newbies on how to strategise their game with the scarce resources like gems, @Sannee.
@ viking99, yes it is quite a lot in comparative. Only because I didn't spent them much. I didn't purchase all of them except for a couple of times, one on piggy bank and another on clam offer of 800. The rest? All faithfully collected from the petting, daily habitat's offer, Otto's wheel, and later, from the dungeon, for the last 3 years. It was slow going at first but started building up fairly fast at one time when the ads offered extra gems when you participated in their interactive ads. I know a lot of people don't find Otto's wheel fanciful, but this has been a constant source of daily steady collection for me.
As for spending them, I couldn't find anything that I felt like spending on, even on events like Ancient. Except for last Ancient which I dropped 1,500 gems to get the tickets for the Soft. I am thinking of dropping some more on this event because I like the designs of the collection and I want to have a void in my team. The only one other event I do spent on is the gem-spending event if it offers good dragons.
@Airbender1505, I get what you meant by not spending on food or gold. I won't spend on gold for sure, but food? I may consider it because my teams are still fairly mid-level. The highest is at 42, 4*. The bites get pretty expensive as the level goes up and I don't want to level a few dragons only but a whole team of 12 dragons together. So even with my current stock of 1.14B stockpile, I don't think that will get me far. I may added that I don't necessarily want to level them up at one shot but gradually because the gameplay is such that the opponents get levelled up correspondently. Right now, I am comfortable with the level as I still have few good dragons to collect at this level. That is a good tip of 5-chest bundle for sigils. I must have missed them out when they made their appearance. I will be on the lookout for them now that I know. Portal has maxed already but hatchery in on Level 4 and yes, 2500 gems to max is also a bit too stiff for me, even with the 16K.
Yes, I agreed with you @cryscryb on the earlier purchases of Boss, but I also stopped buying them after acquiring 5 of them. But having abundant gold is currently still useful to me because I want to grow my food pile to 2B plus like LavrentLo

. Like LadyDraco, I would probably go to buy them to complete the codex. Talking about codex, how high on the priority list is this with you, guys?
Relics are good to get but currently with the cap on, I could hardly add on with what I have in my inventory. Except for the den, I hardly use any of them.
At this point, I would very much like to stay away from the events and get back to what I fell in love with the game in the first place - collecting dragons, and enjoying the dragons I have in my stable, especially the babies. I still have over 80 eggs to hatch and I couldn't for lack of space. That is why I am looking at opening up the 3rd slot in the legendary habitats - to keep all the babies in one island
(a nod to someone who once suggested an island just for babies, yes, please Gamesloft, do do do have one in the offering), also because I am already maxed out at my level. And sadly there aren't many dragons left to breed and most of them now is collectible by events or battles which does take a spark out of the fun that game has to offer.
@LadyDraco, I don't have a clan to help out as I am a single-player clan.
@stachys, oh, I definitely would not spend them all. Being a die-hard hoarder, I would leave a threshold of 10K to be comfortable?

and ya @Moon Rabbit, how did you spend yours? I mean idiotically or not, the gems were sort of given 'free' and so it is right to give it back to the game. I know I have 'wasted' a few thousands of them over the years too but the 'pain' got passed rather quickly when the stock level get replenished pretty fast. That is the one thing I noticed - when you spend the resources, the game give it back fairly soon enough. That's probably get me hooked to the game despite all the whatnots and 'gripes'.