Is there a similiar saying for czech "dolů ti pomůže každý, ale nahoru musíš sám" in english?

Dolů ti pomůže každý, ale nahoru musíš sám

The quote translated means something like

Everyone will drag you down, but you have to find your way up on your own.

Is there something like that in english?

The idea of success in the face of adversity is a common one -- being a human is difficult, no matter what language(s) you may speak! The idiom you describe has a couple of elements in it:

• Others may try to hinder your progress.
• But don't let that stop you; perservere in the face of adversity.

In English, a close translation of this idiom would be along the lines of

If at first you don't succeed -- try, try again.

more grimly expressed in Winston Churchill's quote,

If you are going through hell, keep going.

These are more general ideas and don't explicitly say that the reason for the difficulty is other people -- but the general tone of "persevere in the face of adversity" is meant to apply no matter where the adversity comes from.

A variation of "It's lonely at the top" captures the second element of your expression: "It's lonely getting to the top," but not the first.

There's no elevator to the top conveys the difficulty involved, but not so much that it's the fault of others.

English has both "Misery loves company" (on the one hand) and "Success has many friends" (on the other). It also has a proverb much opposed to the tendency of the Czech saying, as reported in The Facts on File Dictionary of Proverbs (1983):

Great trees keep down the little ones.

which would seem to justify the animosity of the unsuccessful toward the successful because of the damage that the successful person's greatness does to their own prospects. But what I haven't been able to find in English is a saying to this effect:

One's success is an affront to another's failure.

which would help explain the phenomenon of resenting another person's success as arising not so much out of envy as out of the difficulty it poses for the unsuccessful person's self-justification.