Everyone starts off with 100% VP regardless of your SP. Every time you upvote you use up some of your VP, and your VP recharges by 20% each day. This is from Steemit FAQ
How many times can I vote without depleting my voting power?
Every 100% vote you cast will use 2% of your remaining voting power. Your voting power will recharge by 20% each day. You can vote more than 10 times per day, but each vote will be worth less, and it will take longer to reach full voting power again.
Therefore, technically you can't grow your VP. The only thing you can grow is your SP. Together, VP and SP determines how much your upvote attributes to a post from the reward pool.
By the way, this point is in relation to your statement "In order to grow the voting power you have to invest in the platform"
I understand now, thanks for clearing it up. There is confusion in terms there, you are correct.