All the toiling and hard work of last 2-3 years will go in vain if you fail to make the correct choices. As you value every penny of your money. Similarly, you need to value every single digit of your rank which you have earned with your consistent effort and try to get the best out of it. Getting a seat which is also available to a 500/1000 rank lower than you will tantamount to doing injustice with your own rank.
The JOSAA system will allot the first choice to Rank 1 and then only will it move further similarly it will give the best available choice from top preference onwards to Rank-5000 then only it will move to Rank-5001.
So in any case there won’t be a single case where a particular seat is denied to candidate X with higher rank and allotted to candidate Y with lower rank provided that particular choice must have been positioned by candidate X at higher preference than the allotted seat.