for every 1 invested BTC I will receive 6.25 BYTE? Did I understand correctly?
For 1 linked BTC (because you don't invest) will receive 62.5 MB (Megabyte) where 1 MB = 1 000 KB (Kilobytes) = 1 000 000 byte.
For each byte you have, you will receive 0.1 byte (+0.21111 blackbyte if your bytes are on linked byteball addresses).
What is traded for the time being is GB (Gigabyte) where 1 GB = 1 000 MB. For the time being 1 GB trades for around 0.08 BTC.
So if I'd bother to sell some alts in order to link say 5 BTC I'd get 312,5 MB (0.31 GB). This would be currently worth...0.024 BTC (~$24). Correct? Quite a modest amount but perhaps it might be worth it.
Indeed, you would have received 5*1.4 GBs=7GBs, which at todays price 0.08 would be worth 0.56BTC which is $582 if you had done this on the first round.
What you link now and if you keep the bytes, you will have 10% on the bytes, for every future round on all the bytes you hold, and the average BTC linked address ratio to bytes will change down.
If you have today 1GB, after 11 distribution rounds will grow to be 2.85GB.