Has Steamgifts grown in users dramatically last trimester?

Most new users are leeches. Thus your point is invalid :(

ofc there are tricks to win GiveAways! Enter proper GiveAways! ;p

(number of prizes / entries ) * 100 = your chance in %
so just join proper giveaways

it's not what I (we?) mean by entering proper GAs. The thing is that you're probably entering Public non-contributor or <30.01$ CV contributor GiveAways. Plus, as you mentioned you only enter for games you really really want, so probably excluding bundles it leaves public GAs for big titles. Doing so you have like 0,1 - 0,025% to win or less, so with that in mind with your entry number you're actually lucky to win this much. But there are plenty of ways you can greatly improve your chances.

1. A lot of contributors don't want to give good games to "leechers" - meaning ppl who contributed nothing or only boosted their CV using bundle leftovers. You are at 30.00$ CV - it means that if you give away anything that is not on a bundle list, yu will pass the magic barrier of 30.01$ ;p And a lot of better games tend to have at least 30.01$ CV requirement. You can even give away few cents worth DLC and you'll have more opportunities right away.

2. Be active! Your profile suggest that all you do is to go to main site, check GAs, enter and that's all. You don't comment, what prolly mean no forum activity, you're not in any SG-related group, meaning you're not visiting chats etc. And there are a lot of Private GAs happening both on forums and in groups. Even non-puzzle direct clicky on forums will get "only" up to few hundreds entries compared to minimum 1k+ entries in public GAs nowadays. If you solve puzzles there are even better chances to win - rarely a puzzle Ga will have mpore than 50 entries, a lot of times you will see +/- 20 entries which gives you 5% chance to win. Not to mention the fact that by being active you may find friends who will share their private friends-only GAs with you.

3. Join Public Groups! There are quite a lot of public groups on SG. And even if they may have few thousands members it still gives you better chances to win than competing against few hundred thousands users. Public Group GAs tend to have less than 1000 entries, most of the times less than 500.

4. Try to find a GiveAway group - it's the ultimate way to boost your winning chance at SG. There are loads of GiveAway groups on SG, of course each have it's own requirements, but in the end if you want to win more there is no better way. Such a groups gives you opportunity to enter tens of Group-only GAs, usually with max few tens of entrties, which boosts your chances to win dramatically.

All in all the thing is, the more active you are (on forums, chats, in groups, in puzzle sub-community) the biger chance you have to win. On the other hand writing "I don't win" topics on forums will not only not boost your chances in any way, but can even lower them (a lot of big contributors tend to auto-blacklist anyone making such topics, meaning you will be prohibited from entering their GiveAways).