Ryzyko jest zbyt duże.

Because duże has to agree with ryzyko.

• ryzyko is a neuter singular noun
• adjectives in Polish usually match the noun in gender, number, and case

So:

• masculine singular: duży
• feminine singular: duża
• neuter singular: duże

That is why we get Ryzyko jest zbyt duże.

A very common clue is the ending -o. Many Polish nouns ending in -o are neuter.

So ryzyko is neuter, and that affects the adjective:

• duże ryzyko
• to ryzyko
• ryzyko jest duże

As always, there are some exceptions in Polish, but -o = often neuter is a very useful rule of thumb.

zbyt modifies the adjective duże and means too in the sense of excessively.

So:

• duże = big / large
• zbyt duże = too big / excessively large

It works a lot like English too before an adjective.

Yes. That is very natural Polish.

Both are correct:

• Ryzyko jest zbyt duże
• Ryzyko jest za duże

A useful difference:

• zbyt often sounds a bit more formal, careful, or written
• za is very common in everyday speech

So if you are speaking casually, za duże may sound more conversational.

In the present tense, Polish normally uses jest in sentences like this.

So the standard full sentence is:

• Ryzyko jest zbyt duże

You may sometimes see or hear Ryzyko zbyt duże, but that is usually:

• elliptical
• headline-like
• stylistically shortened
• not the normal neutral full sentence for a learner to produce

So for standard Polish, keep jest.

It is in the nominative singular.

This sentence is a basic X is Y pattern:

• Ryzyko = subject
• jest = is
• zbyt duże = predicate adjective

The subject is normally in the nominative, so ryzyko stays in its dictionary form here.

In modern standard Polish, after być (to be), predicate adjectives are usually in the nominative.

So:

• ryzyko — nominative
• duże — nominative neuter singular, agreeing with ryzyko

That is why you do not change duże into some other case here.

Yes, Polish word order is fairly flexible.

The neutral order is:

• Ryzyko jest zbyt duże

But you could also say:

• Zbyt duże jest ryzyko — marked, poetic, or contrastive
• Jest zbyt duże ryzyko — usually closer to There is too much risk / The risk is too great, depending on context

For learners, the original order is the safest and most neutral.

A rough English-friendly guide:

• ryzyko ≈ rih-ZIH-kaw
• jest ≈ yest
• zbyt ≈ zbit or zbyt with a short Polish y
• duże ≈ DOO-zheh

A few key sounds:

• rz in ryzyko is pronounced like ż
• ż sounds like the s in measure
• Polish y is not the same as English ee; it is a harder, central vowel
• j in Polish sounds like English y

A more phonetic approximation of the whole sentence:

• RZIH-zih-kaw yest zbit DOO-zheh

Because in modern Polish, rz is usually pronounced like ż.

So ryzyko starts with a sound similar to the s in measure, not a rolled r followed by z.

This is one of those spelling patterns learners simply have to get used to:

• rz often sounds like ż
• but the spelling is still important for writing and grammar

Yes. Polish does not always match English adjective choices word for word.

With ryzyko, Polish can use:

• duże ryzyko / ryzyko jest duże
• wysokie ryzyko / ryzyko jest wysokie

Both are possible. Very roughly:

• duże = large / great
• wysokie = high

In many contexts, wysokie ryzyko is a very common collocation, especially in formal or technical language, but duże is also perfectly understandable and natural.

Here it is being used as a singular abstract noun: risk.

That is why Polish says:

• Ryzyko jest zbyt duże

If you wanted to talk about risks in the plural, you would use:

• ryzyka

For example:

• Te ryzyka są zbyt duże = These risks are too great

Yes.

• Ryzyko jest duże = The risk is large / great
• Ryzyko jest zbyt duże = The risk is too large / too great

So zbyt adds the idea of excess.

The normal negative is:

• Ryzyko nie jest zbyt duże

That means The risk is not too great.

Notice that:

• nie goes before jest
• the rest of the sentence stays the same

You could also say:

• Ryzyko nie jest duże = The risk is not large
• Ryzyko nie jest za duże = The risk is not too large

It is basically neutral, but zbyt makes it sound a little more formal or careful than za.

So:

• Ryzyko jest zbyt duże = neutral to slightly formal
• Ryzyko jest za duże = more everyday and conversational

Both are correct; the choice depends on tone.