I saw that 1 BTC was allocated as the main prize of the contest, but I do not know how honestly the results are summarized and indeed this bitcoin is transferred to the winner. It is more realistic to get a Bitcoin particle through a faucet, but this is too small a part, which is measured in cents.
If the contest creator is reputable and have proof that they really distribute the prize to the real winner and transparent for everything peoples ask then maybe its worth to try to participate on those contest...
Of course, if a well-known brand acts as the organizer or sponsor of the event, then there is no doubt about the honesty of the winner's choice. But we most often see that such an organizer is an unknown company that does not even have its own website, so you should not expect an honest distribution of the prize fund.