I have never seen someone able to achieve 900x to 2000x free spins. You're too lucky if you can get that huge multiplier. I am sure if it hits me, I will think that it's a bug with slight happiness.
Really, 2000x is not that uncommon, IMO. It's hard but definitely not super rare. I have spun the 2000x many times on Deadwood, Sweet Bonanza, Le-bandit, Sugar rush, etc.
I mean I only play popular slot providers.
In my opinion, these slot multiplier contests are very profitable for all slot players. Let's understand this with the following example,
SLOT NAME: X
RTP: 96%
HIGHEST MULTIPLIER: 10000X
Now let's say you are spinning $0.2 bets, so in order to get 10000x ($2000 either in one max win or in a series of big wins like 500x, 1000x etc) you have to spend $2000 + $80(RTP) = $2080. So your theoretical net loss will be $80 after 10000 spins.
Now let's say you get a couple of 2000x or even 500x doins this, there is a high chance that you will get at least a second place in betpanda.io slot multiplier contest which means you will achieve a theoretical profit of 150 - $80 = $70 per week.
If you get 1st prize, which is not that hard after doing 10000 spins the profit will be much bigger ($250 - $80 = $170). Now in this example I have taken the RTP of 96% but there are slots with even 97%+ RTP and those will boost your profitabilty even more.
Now please keep in mind that I have calculated this based on theoretical RTP, this should work mathematically over a large enough sample size, in the short term you might lose. This is to show that with betpanda.io slot contests, this becomes a positive EV to play there, specially considering low numbers of participants.
If you want to point out any mistakes in my reasoning please do.